94 Explorer with codes: 172, 327, 332, 543, 538 | Ford Explorer - Ford Ranger Forums - Serious Explorations

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94 Explorer with codes: 172, 327, 332, 543, 538

martinh67

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City, State
Virginia
Year, Model & Trim Level
'94 XLT
Recently replaced PFE 3 days ago and and cleaned IAC and MAF. She was running great for about 200 miles. Now she is running rough at idle with CEL and the following codes:

KOEO
327 - DPFE or EVP circuit below minimum voltage of 0.2 volts.
543 - When the PCM commanded the fuel pump on, voltage was not detected on FPM.

CM
327 -
332 - EGR valve opening not detected.

KOER
172 - HEGO sensor circuit indicates system lean (right side)
327 -
538 -Insufficient RPM change during KOER dynamic response test/ Operator error.

I checked the input voltage the to the EGR vacuum regulator and read 14VDC. Kinda high I think.

My next step would be to replace the EGR valve. I also replace the EGR vacuum regulator. All vacuum lines seem good.

Should I replace the EGR valve? I'm afraid of throwing $$ into something that can be simple. Any ideas?
 


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Sabik

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Atlanta
Year, Model & Trim Level
95 XLT
Where was you PFE located? I think that it is the same as a PFS?
 




martinh67

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'94 XLT
The PFE on a 94 is located on the driver's side of the intake manifold. For a 95 it is called a DPFE. I believe it's on the same side...
 




Fordmandan87

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is your ex california or fedral emmission and it is a dpfe sensor because it has two hoses on it (differential pressure feedback) regularor is fine did you check voltage with engine running, Id change egr valve look into possible o2 sensor issue
 




martinh67

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It's federal regs. I'll check the input voltage tomm
 




martinh67

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'94 XLT
Replaced the EGR valve. Runs smoother but CEL stays on even after disconnecting neg battery cable. The codes are now as follows:

KOEO: 327- DPFE or EVP circuit below minimum voltage of 0.2 volts.
CM: 327
KOER: 172 - HEGO sensor circuit indicates system lean (right side)
538 - Insufficient RPM change during KOER dynamic response test/ Operator error.
536 - Brake On/Off circuit failure / switch not actuated during KOER test
(536 and 538 was expected)

Is it odd I did not get the 327 code on the KOER? Or is it a dead give away that would lead me to believe something is wrong in the fuel system which may explain the 172 code?

I have not done any voltage checks or fuel pressure tests. (Need to run to parts store to get battery for volt meter and fuel pressure gauge.)
 




Fordmandan87

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how many miles are on it, i had an o2 code on one side just recently i replaced the sensor and the code is gone so it is possible for one side to have a bad sensor (normally if there was something wrong with the engine then both banks would be affected), do you have a u pull it junkyard in your area
 




martinh67

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My X has 175k miles on it. recently bought it for $500 (a steal) I took it to PepBoys and they said it's in the EGR system. Since I replaced all the components, my next steps is to replace the vacuum lines before I mess with the fuel system.

There is Pick n Pull "bone" yard in my neck of the woods. But I am leary going there to buy emission parts. Unless I see a part that looks relatively new.
 




Joe Dirt

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Sounds like when my DPFE gave up the ghost...
 




Fordmandan87

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i have an idea i will copy and paste word for word diagnostic routines from for for your codes. would that work for you?
 




945spd

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if you have a scan tool you can look at the 02 sensor it should go from 0 to no more then .9 volts at first i thought u had a scan tool that converted obd1 to obd2 codes.then i seen the koer.the 538 and the 536 is from not pumping the brake padel and turn the steering wheel back and forth.if you dont have a scan tool i would unhook the battery cables for 10 to 15 minites with the key on. i know it sounds werd about the key on but on some cars they also tell you after 10 to15 minutes to touch the pos neg together and see what codes come back.if 172 does just get a 02 sensor.
 




Cobraguy

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1995 EB & 1999 EB 5.0
Does a 94 have a DPFE??? I don't think so. They have an EVP sensor on top the EGR valve. There are two different colors to get and you may have to grind the shaft to length to get the installed voltage correct. That seems to be SOP with aftermarket sensors. You will need a break out box or meter and probe carefully. But just because you get that code doesn't mean the sensor is bad. If the valve isn't operating as it should, then you will get this code. You need to first test the switch and see if it's working correctly. If so, then you need to check the control system for the EGR valve. May be something as simple as a vacuum line or you may need solenoids. This is not hard to find or repair if you take your time and use the proper tools. Since you have a lean code, I would look carefully at a broken vacuum line. That may be all that's wrong.

I'm sure you know this, but 536 is because you didn't depress the brake pedal when instructed during the KOER test and the 538 is because you didn't goose the throttle during the same test.
 




Fordmandan87

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for code 327 koeo
sensor type/applicible vehicles - DPFE/ (Thunderbird/Cougar (Calif), 3.8L Taurus/Sable (Calif), Thunderbird SC, 3.2L Taurus SHO, Town Car, Mark VIII Crown Victoria/Grand Marquis (Calif) Ranger/Explorer, 3.0L Taurus (Flex Fuel))
DL1 DIAGNOSTIC TROUBLE CODE (DTC) 327:
INDUCE DTC 337
DTC 327 indicates the PFE/DPFE sensor signal is less than the Self Test minimum value of 0.2 volt.

Possible causes:

Damaged PFE/DPFE sensor.
Open harness circuits.
Shorted harness circuits.
Damaged PCM.
Key off.
Disconnect PFE/DPFE sensor.
Jumper VREF circuit to PFE/DPFE circuit at PFE/DPFE sensor vehicle harness connector.
Rerun Key On, Engine Off (KOEO) Self-Test.
Note: If no DTCs are generated, immediately remove jumper and go directly to
Step DL4 .

Is DTC 337 present (ignore all other DTC's)?
Yes No
REPLACE PFE/DPFE sensor. REMOVE jumper. RERUN Quick Test. REMOVE jumper.
GO to DL2 .

DL2 MEASURE VREF CIRCUIT VOLTAGE AT PFE/DPFE SENSOR
Key off.
PFE/DPFE sensor disconnected.
Key on, engine off.
Measure voltage between VREF circuit and SIG RTN circuit at the PFE/DPFE sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
GO to DL3 . GO to Pinpoint Test Step C1 .

DL3 CHECK PFE/DPFE CIRCUIT CONTINUITY
Key off.
PFE/DPFE sensor disconnected.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
Measure resistance between PFE/DPFE circuit at the PFE/DPFE sensor vehicle harness connector and Test Pin 27 at the breakout box.
Is resistance less than 5.0 ohms?
Yes No
GO to DL4 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL4 CHECK PFE/DPFE CIRCUIT FOR SHORTS TO GROUND AND SIG RTN

Key off.
PFE/DPFE sensor disconnected.
Breakout box installed, PCM disconnected.
Measure resistance between Test Pin 27 and Test Pins 40, 46 and 60 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL5 DIAGNOSTIC TROUBLE CODE (DTC) 337:
INDUCE DTC 327
DTC 337 indicates the PFE/DPFE sensor signal is greater than the Self-Test maximum value of 4.8 volts.

Possible causes are:

Damaged PFE/DPFE sensor.
Shorted harness circuits.
Open SIG RTN circuit.
Damaged PCM.
Key off.
Disconnect PFE/DPFE sensor.
Rerun Key On, Engine Off (KOEO) Self Test.
Is DTC 327 present (ignore all other DTC's)?
Yes No
GO to DL6 . GO to DL7 .

DL6 MEASURE VREF CIRCUIT VOLTAGE AT PFE/DPFE SENSOR
Key off.
PFE/DPFE sensor disconnected.
Key on, engine off.
Measure voltage between VREF circuit and SIG RTN circuit at the PFE/DPFE sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
REPLACE PFE/DPFE sensor. RERUN Quick Test. GO to Pinpoint Test Step C1 .

DL7 CHECK PFE/DPFE CIRCUIT FOR SHORTS TO POWER
Key off.
PFE/DPFE sensor disconnected.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
Measure the resistance between Test Pin 27 and Test Pins 26, 37 and 57 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT PFE/DPFE sensor. RERUN Quick Test. SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL8 DIAGNOSTIC TROUBLE CODE (DTC) 335:
REMOVE GARAGE FORCED AIR
DTC 335 indicates the PFE/DPFE sensor is out of Self-Test range.

Possible causes are:

Damaged PFE/DPFE sensor.
Obstructed pressure inlet hose(s).
Garage exhaust ventilation system affecting PFE/DPFE sensor operation.
Note: PFE/DPFE system can sense a lack of pressure in the vehicle exhaust system. An efficient garage exhaust ventilation system that is installed during Key On Engine Off (KOEO) DTM may generate a DTC 335.

Remove garage forced ventilation system and properly vent to atmosphere.
Rerun KOEO Self-Test.
Is DTC 335 present?
Yes No
GO to DL9 . ADDRESS other DTC's in KOEO Self-Test. If none, CONTINUE with remaining Quick Test.

DL9 CHECK PFE/DPFE SENSOR PRESSURE INPUT HOSE(S)
Remove each pressure input hose from PFE/DPFE sensor.
Inspect each hose and PFE/DPFE sensor inlet(s) for blockage.
Is blockage present?
Yes No
SERVICE as necessary. RERUN Quick Test. RECONNECT pressure input hose(s). GO to DL10 .

DL10 MEASURE VREF CIRCUIT VOLTAGE AT PFE/DPFE SENSOR
Key off.
Disconnect PFE/DPFE sensor.
Key on, engine off.
Measure voltage between VREF circuit and SIG RTN circuit at PFE/DPFE sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
REPLACE PFE/DPFE sensor. RERUN Quick Test. RECONNECT PFE/DPFE sensor. GO to Pinpoint Test Step C1 .

DL11 DIAGNOSTIC TROUBLE CODE (DTC) 558:
MEASURE EVR SOLENOID RESISTANCE
DTC 558 indicates a failure in the EGR Vacuum Regulator (EVR) solenoid or circuit.

Possible causes are:

Damaged EVR solenoid.
Open harness circuit.
Shorted harness.
Damaged PCM.
Key off.
Disconnect EVR solenoid.
Measure EVR solenoid resistance.
Is solenoid resistance between 20 and 70 ohms?
Yes No
GO to DL12 . REPLACE EVR solenoid. RERUN Quick Test.

DL12 CHECK VPWR CIRCUIT VOLTAGE AT EVR SOLENOID
Key on, engine off.
EVR solenoid disconnected.
Measure voltage between battery negative terminal and VPWR circuit at EVR solenoid vehicle harness connector.
Is voltage less than 10.5 volts?
Yes No
SERVICE open circuit. RERUN Quick Test. GO to DL13 .

DL13 CHECK EVR CIRCUIT CONTINUITY
Key off.
EVR solenoid disconnected.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
Measure resistance between Test Pin 33 at the breakout box and EVR circuit at the EVR solenoid vehicle harness connector.
Is resistance less than 5.0 ohms?
Yes No
GO to DL14 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL14 CHECK EVR CIRCUIT FOR SHORTS TO POWER OR GROUND
Key off.
EVR solenoid disconnected.
Breakout box installed, PCM disconnected.
Measure resistance between Test Pin 33 and Test Pins 37 and 57 at the breakout box.
Measure resistance between Test Pin 33 and Test Pins 40 and 60 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. If DTC 558 is repeated, REPLACE PCM.

DL20 DIAGNOSTIC TROUBLE CODE (DTC) 326:
REMOVE GARAGE FORCED VENTILATION
DTC 326 indicates the PFE circuit voltage is lower than expected at zero EVR duty cycle.

Possible causes are:

Obstructed vacuum hose.
Contaminated EVR filter.
Damaged EGR valve.
Damaged EVR solenoid.
Garage exhaust ventilation system.
Note: PFE system can sense a lack of pressure in the vehicle exhaust system. An efficient garage exhaust ventilation system that is installed during Key On Engine Running (KOER) Self-Test may generate a DTC 326.

Remove garage forced ventilation system and properly vent to atmosphere.
Rerun KOER Self-Test.
Is DTC 326 present?
Yes No
GO to DL21 . ADDRESS other DTCs in KOER Self-Test. If none, CONTINUE with remaining Quick Test.

DL21 DIAGNOSTIC TROUBLE CODE (DTC) 327:
RERUN SELF-TEST WITH EGR VALVE VACUUM LINE DISCONNECTED

DTC 327 indicates the PFE sensor signal is less than the Self-Test minimum.

Key off.
Disconnect EGR valve vacuum line at valve and plug vacuum line.
Perform Key On Engine Running (KOER) Self-Test.
Is DTC 327 or 326 present?
Yes No
GO to DL22 . CHECK EVR vent and vacuum hose to EGR valve for obstruction. If OK, REPLACE EVR solenoid. RECONNECT all lines. RERUN Quick Test.

DL22 DIAGNOSTIC TROUBLE CODE (DTC) 326 OR 327: INSPECT PFE/DPFE INPUT HOSES
DTC 326 or 327 indicates that DPFE circuit voltage is lower than expected at zero duty cycle.

Key off.
Check PFE/DPFE sensor pressure input hose(s) for obstruction and/or leaks.
Are there any obstructions or leaks?
Yes No
SERVICE as necessary. RECONNECT all lines. RERUN Quick Test. GO to DL23 .

DL23 CHECK PFE/DPFE SIGNAL VOLTAGE WITH ENGINE AT IDLE
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Start engine and idle with transmission in PARK or NEUTRAL.
Measure voltage between Test Pin 27 and Test Pin 46 at the breakout box.
Is voltage less than 2.9 volts (PFE) or 0.2 volt (DPFE)?
Yes No
For DPFE Applications:
REPLACE DPFE sensor. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.
For PFE Applications:
GO to DL24 .
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL24 CHECK EGR VALVE FOR BINDING
The fault has been isolated to either the EGR valve or PFE sensor. Due to the nature of this particular fault, the EGR valve is suspect because of its vulnerability to contamination and carbon build-up from the exhaust flow. If the engine runs rough at idle, this is a good indication that the EGR valve is not fully seated rather than a faulty PFE sensor.

Remove the EGR valve.
Inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. Service as necessary. (Use Rotunda EGR Valve Cleaner 021-80056 or equivalent if needed)
Re-install EGR valve and rerun Key On Engine Running (KOER) Self-Test.
Is DTC 326 or 327 still present?
Yes No
REPLACE EGR valve. REMOVE breakout box. RERUN Quick Test. If either DTC is still present, REPLACE PFE sensor. The original DTC 326 or 327 was the result of the EGR valve not fully seating. Testing complete.

DL25 ENGINE RUNNING DIAGNOSTIC TROUBLE CODE (DTC) 336 OR 337: CHECK FOR EXHAUST RESTRICTION
DTC 336 indicates the PFE circuit voltage is higher than expected at zero EVR duty cycle.

DTC 337 indicates the PFE circuit voltage is above the Self-Test maximum.

Possible causes:

Restricted exhaust system.
Damaged PFE sensor or PCM.
Open harness circuits.
Shorted harness circuits.
Attach vacuum gauge to intake manifold source.
Hook up tachometer.
Observe the vacuum gauge needle while performing the following:
Start engine and gradually increase the rpm from base idle to 2000 rpm with the transmission in NEUTRAL.
Observe the rate of speed of the vacuum gauge needle as it falls and rises while maintaining the increased engine rpm and also note final vacuum reading.
Note: On a non-restricted system, the vacuum gauge needle will drop to zero and then quickly return to normal (above 16 in.). On a restricted system, the vacuum gauge needle will slowly drop to zero and slowly increase as rpm is maintained. The rate of speed at which the vacuum gauge needle returns to normal is much slower on a restricted system.

Is the rate of speed the vacuum gauge needle returns to normal quick and a (minimum) vacuum of 16 inches reached?
Yes No
No restriction in the exhaust system. GO to DL26 . REFER to Section 15A Catalyst and Exhaust Systems for further diagnosis.

DL26 CHECK PFE SIGNAL VOLTAGE
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Start engine and idle with transmission in PARK or NEUTRAL.
Measure voltage between Test Pin 27 and Test Pin 46 at the breakout box.
Is voltage between 3.0 and 3.5 volts?
Yes No
REPLACE PCM. RECONNECT all components. RERUN Quick Test. GO to DL27 .

DL27 CHECK PFE AND SIG RTN HARNESS CIRCUIT CONTINUITY
Key off.
Breakout box connected, PCM disconnected.
PFE sensor disconnected.
Measure resistance between PFE circuit at the sensor vehicle harness connector and Test Pin 27 at the breakout box.
Measure resistance between PFE SIG RTN circuit at the sensor vehicle harness connector and Test Pin 46 at the breakout box.
Is each resistance less than 5.0 ohms?
Yes No
GO to DL28 . SERVICE open circuit(s). REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL28 CHECK PFE HARNESS CIRCUIT FOR SHORTS TO POWER
Key off.
Breakout box connected, PCM disconnected.
PFE sensor disconnected.
Measure resistance between Test Pin 27 and Test Pins 26, 37, and 57 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PFE sensor. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. SERVICE short circuit(s). REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL30 DIAGNOSTIC TROUBLE CODE (DTC) 332:
VERIFY VACUUM IS PRESENT AT EGR VALVE
DTC 332 indicates the PFE/DPFE sensor signal to the Powertrain Control Module (PCM) did not change when the PCM output a duty cycle to the EVR solenoid requesting EGR flow.

Possible causes are:

Vacuum hose leaks.
Obstructed vacuum hoses.
Damaged EVR solenoid.
Damaged PFE/DPFE sensor.
Damaged EGR valve.
Damaged PCM.
Key off.
Disconnect and inspect vacuum hose between EVR solenoid and EGR valve for blockage, kinks, etc. Service as necessary and reconnect after inspection.
Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.
Rerun Key On Engine Running (KOER) Self-Test while observing vacuum gauge.
Is vacuum reading less than 1 in-Hg (3kPa) throughout the test (disregard DTC output)?
Yes No
REMOVE vacuum gauge. GO to DL31 . REMOVE vacuum gauge. RECONNECT EGR valve vacuum hose. RERUN Quick Test if the vacuum hose was not in good condition and service was completed. Otherwise, GO to DL34 .

DL31 CHECK VACUUM INPUT TO THE EVR SOLENOID
Key off.
Disconnect source vacuum hose at EVR Solenoid and connect hose to a vacuum gauge.
Start the engine and let it idle while observing the vacuum gauge.
Is vacuum above 15 inches at idle?
Yes No
INSPECT vacuum hose from EVR Solenoid to EGR valve. If OK, REPLACE EVR solenoid. RERUN Quick Test. REPLACE the vacuum line connecting EVR solenoid to source vacuum. RERUN Quick Test.

DL34 CHECK SIGNAL AT THE PFE/DPFE INLET HOSE(S)
Key off.
Disconnect and inspect the PFE/DPFE inlet hose(s) for kinks, blockages, etc. Service as necessary and reconnect after inspection.
Tee in a standard vacuum gauge at the PFE/DPFE inlet hose (downstream signal).
Rerun KOER Self-Test.
Is there a momentary increase in vacuum gauge reading during KOER Self-Test (indicating EGR valve is opening?
Yes No
REMOVE vacuum gauge. RERUN Quick Test if the inlet hose(s) needed service. If service was not needed, then GO to DL35 . REMOVE and INSPECT the EGR valve for signs of contamination, unusual wear, carbon deposits, grinding, and other damage. SERVICE as necessary (use Rotunda 021-80056 EGR valve cleaner if needed). RERUN Quick Test.

DL35 ATTEMPT TO GENERATE KOEO DTC 337
Key off.
Disconnect PFE/DPFE sensor.
Jumper VREF circuit to PFE/DPFE circuit at the PFE/DPFE sensor vehicle harness connector.
Perform KOEO Self-Test.
Note: If no DTCs are generated, immediately remove jumper and go directly to DL37 .

Is DTC 337 present (ignore all other DTCs)?
Yes No
REPLACE PFE/DPFE sensor. REMOVE jumper wire. RERUN Quick Test. REMOVE jumper. GO to DL36 .

DL36 MEASURE VREF CIRCUIT VOLTAGE
Key off.
PFE/DPFE disconnected.
Key on, engine off.
Measure voltage between VREF circuit and SIG RTN circuit at the PFE/DPFE sensor vehicle harness connector.
Is voltage between 4.0 and 6.0 volts?
Yes No
GO to DL37 . GO to Pinpoint Test Step C1 .

DL37 CHECK PFE/DPFE HARNESS CIRCUIT CONTINUITY

Key off.
PFE/DPFE sensor disconnected.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box, leave PCM disconnected.
Measure resistance between PFE/DPFE circuit at the PFE/DPFE sensor vehicle harness connector and Test Pin 27 at the breakout box.
Is resistance less than 5.0 ohms?
Yes No
GO to DL38 . SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL38 CHECK PFE/DPFE HARNESS CIRCUIT FOR SHORTS TO GROUND AND SIG RTN
Key off.
PFE/DPFE sensor disconnected.
Breakout box installed, PCM disconnected.
Measure resistance between PFE/DPFE circuit at the PFE/DPFE sensor vehicle harness connector and Test Pins 40/60 at the breakout box.
Measure resistance between PFE/DPFE circuit at the PFE/DPFE sensor vehicle harness connector and Test Pin 46 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes No
REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test. SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL50 DIAGNOSTIC TROUBLE CODE (DTC) 336 OR 337: CHECK FOR EVR MALFUNCTION

DTC 336 or 337 indicates that DPFE circuit voltage is higher than expected at zero duty cycle.
Possible causes are:
Damaged EVR solenoid.
Damaged DPFE sensor.
Damaged or contaminated EGR valve.
Vacuum hose routing.
Damaged PCM.
Key off.
Disconnect EGR valve vacuum line at valve and plug line.
Rerun Key On Engine Running (KOER) Self-Test.
Is DTC 336 or 337 present (ignore all other DTCs)?
Yes No
RECONNECT EGR vacuum line. GO to DL51 . VERIFY vacuum line routing is correct. CHECK EVR filter for contamination or blockage. If all OK, REPLACE EVR solenoid. RECONNECT all lines. RERUN Quick Test.

DL51 CHECK DPFE SIGNAL VOLTAGE WITH ENGINE AT IDLE
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Start engine and idle with transmission in PARK or NEUTRAL.
Measure voltage between Test Pin 27 and Test Pin 46 at the breakout box.
Is voltage greater than 0.7 volt at idle?
Yes No
GO to DL52 . REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

DL52 CHECK EGR VALVE FOR BINDING
The fault has been isolated to either the EGR valve or DPFE sensor. Due to the nature of this particular fault, the EGR valve is suspect because of its vulnerability to contamination and carbon build-up from the exhaust flow. If the engine runs rough at idle, this is a good indication that the EGR valve is not fully seated rather than a faulty DPFE sensor.

Remove the EGR valve.
Inspect the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. Service as necessary. (Use Rotunda EGR Valve Cleaner 021-80056 if needed.)
Reinstall EGR valve and rerun KOER Self-Test.
Is DTC 336 or 337 still present?
Yes No
REPLACE EGR valve. REMOVE breakout box. RERUN KOER Self-Test. If DTC 336 or 337 is still present, REPLACE DPFE sensor. The original DTC 336 or 337 was the result of the EGR valve not fully seating. Testing complete.

DL90 ALL CONTINUOUS MEMORY EGR DIAGNOSTIC TROUBLE CODES (DTC): INTERMITTENT VERIFICATION
Note: This test step verifies if the DTC is due to an intermittent or a hard fault.

Perform KOEO and KOER Self-Test if you have not already done so and make note of all codes received in KOEO, Continuous Memory and KOER modes. If unable to run KOER due to a "No Start" or "Stall," do not continue with this step, but go directly to DL101 .
If an EGR fault exists at the time of this test (hard fault), then an EGR DTC should also be received in KOEO or KOER or both depending on the DTC. If the EGR DTC is NOT received in KOEO or KOER but only retrieved from Continuous Memory, this could be due to an intermittent EGR system fault which occurred sometime in the past.
Are there any DTCs output in KOEO or KOER Self-Test (ignore Continuous Memory DTC's at end of KOEO)?
Yes No
A hard fault is indicated. RETURN to Section 2A and REFER to the EEC-IV DTC charts. An intermittent fault is indicated. GO to DL91 .

DL91 ALL CONTINUOUS MEMORY EGR DIAGNOSTIC TROUBLE CODES (DTC): VISUAL INSPECTION
Key off.
Conduct a thorough visual inspection of the PFE/DPFE system for any potential failures. Use the following check list for possible causes:
Obvious physical damage.
Loose connectors.
Pushed out connector pins.
Corroded connector contacts.
Damaged wiring insulation.
Incorrect harness routing.
Incorrect component mounting.
Road salt or rust accumulation.
Damaged vacuum hoses.
Incorrect vacuum hose routing.
EVR solenoid filter contamination.
Vacuum hose restriction.
Road splash or icing.
Incorrect service parts.
Does the EGR system visual inspection reveal a potential failure?
Yes No
SERVICE fault as necessary. CLEAR Continuous Memory. (REFER to Quick Test Appendix, Section 5A ) RERUN Quick Test. RECONNECT all components. GO to DL92 .

DL92 ALL CONTINUOUS MEMORY EGR DIAGNOSTIC TROUBLE CODES (DTC): CODE DEFINITIONS AND DIRECTION
Select the DTC in question and follow the "Action to Take" direction.
DTC 327 (PFE/DPFE) PFE/DPFE signal less than the allowable minimum voltage. DTC 337 (PFE/DPFE) PFE/DPFE signal greater than the allowable maximum voltage. DTC 336 (PFE) Exhaust pressure high/PFE signal higher than expected. DTC 336 (DPFE) DPFE signal higher than expected. DTC 326 (PFE) PFE signal lower than expected. DTC 332 (PFE/DPFE) Insufficient EGR flow detected.
GO to DL93 . GO to DL93 . GO to DL93 . GO to DL93 . GO to DL93 . GO to DL105 .

DL93 DTCS 326, 327, 336, 337: WIGGLE TEST SENSOR
Possible Causes:
DTCs 337 (PFE/DPFE), 336 (PFE/DPFE)

Open in PFE/DPFE SIG RTN circuit.
Short to PWR or VREF in PFE/DPFE Signal circuit.
DTC 336 (PFE)

Obstructed PFE sensor inlet.
DTCs 327 (PFE/DPFE), 326 (PFE)

Open in PFE/DPFE Signal circuit.
Open in PFE/DPFE VREF circuit.
Short to GND in either PFE/DPFE Signal or VREF circuits.
DTCs 327 (PFE), 326 (PFE), 336 (DPFE), 337 (DPFE)

EGR valve sticking open.
EVR solenoid sticking open.
EVR solenoid vent restricted.
EVR solenoid driver shorting to GND.
Note: All circuit faults can be in the component, harness or PCM.

Enter Engine Running Continuous Monitor DTM (Refer to Quick Test Appendix, Section 5A ).
Observe VOM or STAR LED or indication of a fault while performing the following:
Lightly tap on PFE/DPFE sensor and wiggle the sensor vehicle harness connector (to simulate road shock).
Is a fault indicated?
Yes No
INSPECT connectors and terminals. If OK, REPLACE PFE/DPFE sensor. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. GO to DL94 .

DL94 WIGGLE TEST EEC-IV VEHICLE HARNESS
Still in Engine Running Continuous Monitor DTM.
Observe VOM or STAR LED for a fault indication while performing the following:
Grasp the vehicle harness closest to the PFE/DPFE sensor connector. Wiggle, shake or bend a small section of the EEC-IV system vehicle harness while working your way to the dash panel. Also wiggle, shake or bend the EEC-IV vehicle harness from the dash panel to the PCM.
Is a fault indicated?
Yes No
ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. GO to DL95 .

DL95 CHECK PCM CONNECTOR
Key off.
Disconnect PCM connector.
Inspect both connectors and connector terminals for obvious damage or faults.
Are connectors and terminals OK?
Yes No
For DTCs 327 (PFE), 326 (PFE), 336 (DPFE), 337 (DPFE):
GO to DL96 .
For DTC 336 (PFE):
GO to DL100 .

All others:
Unable to duplicate and/or identify fault at this time. For further diagnosis using EEC-IV Monitor Box or Scan Tool, REFER to Section 7A . All others, RERUN Quick Test.
SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL96 CHECK EGR VALVE FOR STICKING
If customer complaint includes a rough idle or stall, the EGR valve could be sticking open or a fault in the EVR solenoid vacuum control could be forcing the EGR valve to open when not desired.

Key off.
Disconnect vacuum hose at EGR valve and plug end of hose.
Connect a hand vacuum pump to the EGR valve.
Apply (10 in-Hg) 34 kPa of vacuum to EGR valve and release while observing movement with inspection mirror if possible. Look for binding of the valve pintle.
Does the EGR valve function in a smooth manner?
Note: Repeat test as necessary to ensure accurate results.

Yes No
GO to DL97 . REMOVE AND INSPECT the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. SERVICE as necessary (USE Rotunda EGR valve cleaner 021-80056 if needed). CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL97 CHECK EVR SOLENOID AND HOSES
An EVR solenoid that is not functioning properly can cause the EGR valve to open or remain open when EGR is NOT demanded (such as at idle).

Key off.
Inspect the EVR solenoid vacuum hoses and solenoid closely for the following:
Restriction in the vacuum hoses.
Signs of contamination, icing or moisture at EVR and in hoses.
Excessive contamination in the EVR filter.
Is a fault indicated?
Yes No
ISOLATE fault and SERVICE as necessary. RECONNECT all components. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. RECONNECT all components. GO to DL98 .

DL98 CHECK EVR SOLENOID FOR SHORTS
An EVR solenoid or EVR driver circuit short could cause the EVR to open supplying the EGR valve with vacuum.

Key off.
Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.
Run engine to operating temperature and stabilized idle.
With the engine at idle, tap the EVR solenoid and wiggle the EVR connector while noting vacuum reading.
Does the EGR vacuum remain below 3.4 kPa (1.0 in-Hg) with no sudden increase?
Note: EVR leakage below 3.4 kPa (1.0 in-Hg) is normal.

Yes No
LEAVE vacuum gauge connected. GO to DL99 . INSPECT EVR solenoid connector for shorts. SERVICE as necessary. If OK, SERVICE or REPLACE EVR solenoid. RECONNECT all components. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL99 CHECK EVR HARNESS CIRCUIT FOR INTERMITTENTS BETWEEN EVR AND PCM
Vacuum gauge connected.
Key on, engine running.
Look for an increase in EGR vacuum while performing the following:
With the engine at idle, wiggle the EVR solenoid harness between the EVR solenoid and dash panel and between dash panel and Powertrain Control Module (PCM).
Does the EGR vacuum increase?
Yes No
ISOLATE and SERVICE short in EVR circuit. REMOVE vacuum gauge. RECONNECT all components. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to Section 7A .

DL100 INSPECT PFE SUPPLY HOSE FOR BLOCKAGE
Key off.
Remove PFE sensor and inspect sensor supply inlet for liquids and/or any type of blockage.
Inspect PFE supply hose to EGR valve base for liquids and/or blockage.
Is supply hose or sensor restricted with liquid or other blockage?
Yes No
CLEAN and/or SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to Section 7A . All others, CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL101 CHECK VACUUM AT EGR VALVE
This step checks if the EGR valve is receiving vacuum forcing it to open upon start-up.

Disconnect and plug vacuum hose at the EGR valve.
Start engine and let idle if possible.
Will the engine start and idle normally?
Yes No
INSPECT EVR vacuum hoses for correct routing. If OK, REPLACE EVR solenoid. RECONNECT all components. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. GO to DL102 .

DL102 CHECK FOR STUCK OPEN EGR VALVE
Key off.
Connect a hand vacuum pump to the EGR valve.
Apply 34 kPa (10 in-Hg) of vacuum to EGR valve and release. Use an inspection mirror to observe valve movement or listen for valve closing shut. Repeat several times to verify valve function. The valve may have to be removed in order to determine its condition.
Is EGR valve stuck in the open position or not fully reseating?
Yes No
REMOVE and INSPECT the EGR valve for signs of contamination, unusual wear, carbon deposits, binding, and other damage. SERVICE as necessary (Use Rotunda EGR valve cleaner 021-80056 if needed). CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. The "No Start" or "Stall" symptom is not due to the EGR system. RECONNECT all components. RETURN to the appropriate Diagnostic Routine Flowchart in Section 2A and continue to diagnose the symptom prior to servicing the EGR Continuous DTC's.

DL105 DTC 332: CHECK EGR VALVE OPERATION
Possible Causes:

DTC 332 (PFE/DPFE)

EGR valve sticking closed.
EGR valve diaphragm leaks.
EVR solenoid sticking closed.
Loss of vacuum to or from EVR.
Open in EVR VPWR or driver circuits.
Leak or restriction in PFE/DPFE signal hoses.
Key off.
Connect a vacuum pump to the EGR valve.
While observing the EGR valve, slowly apply 34 kPa (10 in-Hg) vacuum.
Note: EGR valve should begin to open with a small amount of vacuum, 3 to 5 kPa (1 to 1.5 in-Hg), and be fully open with about 13 kPa (4 in-Hg). EGR valve should remain open with vacuum applied. Diaphragm could be leaking if the valve closes immediately.

Does the EGR valve open smoothly and hold vacuum?
Yes No
GO to DL106 . REMOVE and INSPECT the EGR valve for signs of diaphragm damage or leakage, contamination, unusual wear, carbon deposits, binding, and other damage. SERVICE as necessary (Use Rotunda EGR valve cleaner 021-80056 if needed). CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL106 INSPECT EVR SOLENOID HOSES
Key off.
Disconnect EVR vacuum hoses.
Verify that hoses are clear of any obstructions, properly routed and will hold vacuum.
Are EVR vacuum hoses in good condition?
Yes No
RECONNECT EVR hoses. GO to DL107 . SERVICE vacuum hoses as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.

DL107 INSPECT PFE/DPFE SIGNAL LINE(S)
Key off.
Disconnect PFE/DPFE signal hoses at the sensor.
Inspect sensor and signal line(s) for any signs of contamination, obstruction or leaks.
Is there a fault indicated?
Yes No
ISOLATE fault and SERVICE as necessary. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. RECONNECT ALL COMPONENTS. GO to DL108 .

DL108 INSPECT EVR SOLENOID
Key off.
Disconnect Powertrain Control Module (PCM) connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box and connect PCM to breakout box.
Disconnect vacuum hose at EGR valve and connect hose to a vacuum gauge.
Run engine to operating temperature and stabilized idle.
Jumper Test Pin 40 to Test Pin 33 at the breakout box which should turn ON the EVR solenoid.
While reading the vacuum gauge, tap the EVR solenoid, wiggle the solenoid connector and solenoid vehicle harness. Look for a sudden drop in vacuum reading as each action is performed.
Is there a fault indicated?
Yes No
ISOLATE and SERVICE fault as necessary. RECONNECT all components. CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test. Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, REFER to Section 7A . All others CLEAR Continuous Memory (REFER to Quick Test Appendix, Section 5A ). RERUN Quick Test.
 




Cobraguy

Explorer Addict
Joined
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City, State
Phoenix...Greatest City on Earth
Year, Model & Trim Level
1995 EB & 1999 EB 5.0
Jesus! I think a couple of birthdays came and went reading that!
 




martinh67

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'94 XLT
Thanks Fordmandan! I assume you got this from a Mitchlle manual? I recently check it out from the library and scanned the Explorer section. (Wahta pain in the arse!) The wiring diagrams are worth as gold and easy to read/follow. I will go through the DL steps and let you know "Whisky, Tango, Foxtrot" going on.
 




martinh67

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Checked fuel. Readings as follows:
KOER - 28 PSI (2 psi below specs)
KOEO - 37 PSI (within spec)

Does this explain why I get a 172 code? (Engine running lean)

As a result, does the PCM tell the fuel regulator to pump more fuel?

Can the high pressure fuel pump and/or fuel regualer be faulty?

Is it safe to assume code 327 has nothing to do with code 172, or vise eversa?
 




Fordmandan87

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City, State
Royston, G.A.
Year, Model & Trim Level
in process of purchase
nope i got that from the fordtechservice web site that the ford service techs have access to (one of the benefits of workin for ford) fuel pressure is fine and is not causing the code your o2 sensor is probably defective 327 is unrelated to 172
 




martinh67

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My public library has them. I'm in process of scanning the explorer pages
 




martinh67

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City, State
Virginia
Year, Model & Trim Level
'94 XLT
Yessssssssssssssssssssss!!!!!!

After extensive wire and electron chasing, I finally determined that I received a bad DFPE from AZ. Luckly, it was under a 2 yr warrenty. No check engine "idiot" light on and KOEO and KOER passed. (odd because code 172 went away as well...)

Idle roughness has ebated about 75%. Something I can live with. Hoping this would increase my gas milage.
 


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martinh67

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Gas milage is up...went from 12 mpg to 18.5
 




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