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code p0420 low cat efficiency

snicklfritz

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96 ford explorer
:( well check engine light came on in my explorer its a 96 with a 4.0 it is saying p0420 low cat efficiency and i have done a search on this forum but could not find the info. on this code then i googled it and it seems that a slow o2 sensor will cause this or a vac leak has any one had this issue should i try o2 sensors first any help would be appreciated
 


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drdoom

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I don't know...that is a code I have seen, I cleared it and it never came back. I would not just put sensors on there without testing them first to see if they are bad.
 




swetrid

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Ford has tsb for reflash of pcm, i would try this first.
Printable View (12 KB)
TSB
00-26-4 MALFUNCTION INDICATOR LAMP (MIL) - MIL ILLUMINATED - DIAGNOSTIC TROUBLE CODE (DTC) P0420 STORED IN MEMORY - VEHICLES EQUIPPED WITH 4.0L OHV ENGINE ONLY
LAMP - MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATED - DIAGNOSTIC TROUBLE CODE (DTC) P0420 STORED IN MEMORY - VEHICLES EQUIPPED WITH 4.0L OHV ENGINE ONLY

Publication Date: DECEMBER 14, 2000

FORD: 1996 EXPLORER


This article is being republished in its entirety to update the Calibration Information.

ISSUE:
Some vehicles may exhibit a Malfunction Indicator Lamp (MIL) illumination along with a P0420 Diagnostic Trouble Code (DTC) stored in continuous memory with no driveability concerns. This may be caused by the calibration of the Powertrain Control Module (PCM).

ACTION:
If no other failures are observed during normal diagnosis, (physically damaged catalyst, stuck fuel injectors, etc.), reprogram the PCM with the latest level calibration in the application chart. PCM reprogramming should be performed before any emission hardware is replaced. If the vehicle already has the latest calibration, follow normal diagnostic procedures for DTC.

NOTE: PCM REPROGRAMMING SHOULD BE PERFORMED BEFORE ANY EMISSION HARDWARE IS REPLACED.



PCM CALIBRATION INFORMATION
Application Old Part Number (-12A650-) New Part Number (-12A650-) Old Tear Tag New Tear Tag Old Calibration New Calibration NGS/SBDS Qualifier
Explorer - 49 State M/T F6PF-MC F6PZ-MD MXD2 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AA F6PZ-MD ABE0 MXD3 6-57B-R00 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AB F6PZ-MD ABE1 MXD3 6-57B-R05 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F6PF-MA F6PZ-MD SDO0 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AC F6PZ-MD ABE2 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F6PF-MB F6PZ-MD MXD0, MXD1 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration

Explorer - California M/T F6PF-NC F6PZ-ND SDO2 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BA F6PZ-ND BAD0 SDO3 6-57R-R00 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BB F6PZ-ND BAD1 SDO3 6-57R-R05 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BC F6PZ-ND BAD2 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F6PF-NA F6PZ-ND SDO0 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F6PF-NB F6PZ-ND SDO1 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration

Explorer 49 State A/T F6PF-KB F6PZ-KC KDP1 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F67F-DA F6PZ-KC MKK0 KDP2 6-58B-R00 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F6PF-KA F6PZ-KC KDP0 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F67F-DC F6PZ-KC MKK1, MKK2 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration

Explorer - California A/T F6PF-LB F6PZ-LC LLA1 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration
Explorer - California A/T F67F-FA F6PZ-LC FAB0 LLA2 6-58R-R00 6-58R-R00 6-58R Calibration
Explorer - California A/T F67F-FB F6PZ-LC FAB1 LLA2 6-58R-R05 6-58R-R10 6-58R Calibration
Explorer - California A/T F67F-FC F6PZ-LC FAB2 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration
Explorer - California A/T F6PF-LA F6PZ-LC LLA0 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration


Obtain an Authorized Modifications Decal (FPS 8262 - obtainable through DOES II, 25/pkg) and list the date, dealer number, and summary of modifications performed. Select a prominent place adjacent to the Vehicle Emission Control Information Decal suitable for installing the Authorized Modifications Decal. Clean the area, install the decal, and cover it with a clear plastic decal shield.

AUTHORIZED MODIFICATIONS

THE FOLLOWING MODIFICATIONS HAVE BEEN MADE:
Reprogrammed Powertrain Control Module (PCM) per TSB 00-26-4



THESE MODIFICATIONS HAVE BEEN APPROVED, AS APPROPRIATE, BY EPA AND CARB.
DEALER NUMBER:------------------------------------------DATE:

CHANGE AUTHORITY:

FPS 8262 9/78 FORD MOTOR COMPANY PRINTED IN U.S.A.





OTHER APPLICABLE ARTICLES:
NONE

SUPERSEDES:
00-23-4

WARRANTY STATUS:
Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage And Emissions Warranty Coverage

DEALER CODING
BASIC PART NO. CONDITION CODE
RECALEM 42

OASIS CODES:
698298


--------------------------------------------------------------------------------

Copyright © 2000 Ford Motor Company
 




snicklfritz

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so i am second owner dont think that the first owner did anything to this explorer should i just call dealer find out how much it is
 




drdoom

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This is what the sticker looks like, showing it has been done. I found this one on the radiator support.
exp_mod_sticker1101.jpg
 




snicklfritz

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nope does not have one sense does not have then i have to go to dealer and do you think they will charge me
 




swetrid

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We usually charge like $45 for pcm update.
 




bobflood

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I don't know...that is a code I have seen, I cleared it and it never came back. I would not just put sensors on there without testing them first to see if they are bad.

+1 for this. My '97 5.0 throws this code once a year or so; turn it off and it stays off for months and months - been doing it literally for years. I would wait for some other code to point me in a specific direction.
 




snicklfritz

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problem is i live in california and its smog time i am going to call dearer in tyhe morning to see whats up thank you for the reply's
 




snicklfritz

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Messages
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96 ford explorer
Ford has tsb for reflash of pcm, i would try this first.
Printable View (12 KB)
TSB
00-26-4 MALFUNCTION INDICATOR LAMP (MIL) - MIL ILLUMINATED - DIAGNOSTIC TROUBLE CODE (DTC) P0420 STORED IN MEMORY - VEHICLES EQUIPPED WITH 4.0L OHV ENGINE ONLY
LAMP - MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATED - DIAGNOSTIC TROUBLE CODE (DTC) P0420 STORED IN MEMORY - VEHICLES EQUIPPED WITH 4.0L OHV ENGINE ONLY

Publication Date: DECEMBER 14, 2000

FORD: 1996 EXPLORER


This article is being republished in its entirety to update the Calibration Information.

ISSUE:
Some vehicles may exhibit a Malfunction Indicator Lamp (MIL) illumination along with a P0420 Diagnostic Trouble Code (DTC) stored in continuous memory with no driveability concerns. This may be caused by the calibration of the Powertrain Control Module (PCM).

ACTION:
If no other failures are observed during normal diagnosis, (physically damaged catalyst, stuck fuel injectors, etc.), reprogram the PCM with the latest level calibration in the application chart. PCM reprogramming should be performed before any emission hardware is replaced. If the vehicle already has the latest calibration, follow normal diagnostic procedures for DTC.

NOTE: PCM REPROGRAMMING SHOULD BE PERFORMED BEFORE ANY EMISSION HARDWARE IS REPLACED.



PCM CALIBRATION INFORMATION
Application Old Part Number (-12A650-) New Part Number (-12A650-) Old Tear Tag New Tear Tag Old Calibration New Calibration NGS/SBDS Qualifier
Explorer - 49 State M/T F6PF-MC F6PZ-MD MXD2 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AA F6PZ-MD ABE0 MXD3 6-57B-R00 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AB F6PZ-MD ABE1 MXD3 6-57B-R05 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F6PF-MA F6PZ-MD SDO0 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F67F-AC F6PZ-MD ABE2 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration
Explorer - 49 State M/T F6PF-MB F6PZ-MD MXD0, MXD1 MXD3 6-57B-R10 6-57B-R10 6-57B Calibration

Explorer - California M/T F6PF-NC F6PZ-ND SDO2 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BA F6PZ-ND BAD0 SDO3 6-57R-R00 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BB F6PZ-ND BAD1 SDO3 6-57R-R05 6-57R-R10 6-57R Calibration
Explorer - California M/T F67F-BC F6PZ-ND BAD2 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F6PF-NA F6PZ-ND SDO0 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration
Explorer - California M/T F6PF-NB F6PZ-ND SDO1 SDO3 6-57R-R10 6-57R-R10 6-57R Calibration

Explorer 49 State A/T F6PF-KB F6PZ-KC KDP1 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F67F-DA F6PZ-KC MKK0 KDP2 6-58B-R00 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F6PF-KA F6PZ-KC KDP0 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration
Explorer 49 State A/T F67F-DC F6PZ-KC MKK1, MKK2 KDP2 6-58B-R10 6-58B-R10 6-58B Calibration

Explorer - California A/T F6PF-LB F6PZ-LC LLA1 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration
Explorer - California A/T F67F-FA F6PZ-LC FAB0 LLA2 6-58R-R00 6-58R-R00 6-58R Calibration
Explorer - California A/T F67F-FB F6PZ-LC FAB1 LLA2 6-58R-R05 6-58R-R10 6-58R Calibration
Explorer - California A/T F67F-FC F6PZ-LC FAB2 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration
Explorer - California A/T F6PF-LA F6PZ-LC LLA0 LLA2 6-58R-R10 6-58R-R10 6-58R Calibration


Obtain an Authorized Modifications Decal (FPS 8262 - obtainable through DOES II, 25/pkg) and list the date, dealer number, and summary of modifications performed. Select a prominent place adjacent to the Vehicle Emission Control Information Decal suitable for installing the Authorized Modifications Decal. Clean the area, install the decal, and cover it with a clear plastic decal shield.

AUTHORIZED MODIFICATIONS

THE FOLLOWING MODIFICATIONS HAVE BEEN MADE:
Reprogrammed Powertrain Control Module (PCM) per TSB 00-26-4



THESE MODIFICATIONS HAVE BEEN APPROVED, AS APPROPRIATE, BY EPA AND CARB.
DEALER NUMBER:------------------------------------------DATE:

CHANGE AUTHORITY:

FPS 8262 9/78 FORD MOTOR COMPANY PRINTED IN U.S.A.





OTHER APPLICABLE ARTICLES:
NONE

SUPERSEDES:
00-23-4

WARRANTY STATUS:
Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage And Emissions Warranty Coverage

DEALER CODING
BASIC PART NO. CONDITION CODE
RECALEM 42

OASIS CODES:
698298


--------------------------------------------------------------------------------

Copyright © 2000 Ford Motor Company


So if this is the problem can i reset my ECM and drive it around for a little bit then take it in for a smog please tell me what you think thank you
 




snicklfritz

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well got it fixed problem was that the plug wires had twice the resistance that they were supposed to put new motorcraft platinum plugs and new wires on it and the light went off i guess the previous owners had not done a tune up for a really long time electrode was melted away but it still ran pretty good going to clean throttle body and iac today it has a whistle under light load
 




slickemhoundd

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Has anyone done this latetly? Taking it to ford to reflash/update? How much did it cost? Im having the same issue as of the past several months. New egr valve, solenoid, cats tune up. Not because of this code but because it needed them. Its driving me up a wall especially being a mechanic. Go figure i need a new windsheild but cant do it till this issue is resolved!?
 




snicklfritz

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i never went and got it done but i priced it here in california they wanted 85 bucks to do it my problem came back within 200 miles turns out that my last o2 sensor was not reading which was triggering my code for cat put a new o2 in it and still says that its not reading so i am currently looking at the wire connector when i get rear o2 to read and if i still get the code i am going to have computer flashed with updated program
 




slickemhoundd

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i realized after my fiance hydrolocked the motor this is when the light came on shortly after. got me wondering if it is time again to do the cats. or if it couldve effected anything else
 




slickemhoundd

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now im thinking also with the stuck egr (replaced) dumping all the hydrocarbons through the exhaust couldve fouled it. i wish i wasnt so busy so i could drop the cats and inspect... hmph
 




slickemhoundd

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Just an interseting thing i thought. If i clear the dtc with my scanner the code comes back within a day or two. If i disconnect the battery (cleaning terminals) the dtc wont come back for a week. It has fresh plugs and wires, if anything i may do them to frequently just to keep an eye on their condition. Also i contacted holman ford and they said they have no idea why i would need to update the pcm. But theyd take me in for $125 for a diagnosis. Not sure where else to look, it appears the o2's are reading properly in datastream. Im a little lost
 




slickemhoundd

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$129 for reflash or $129 diagnosis and then additional $129 if reflash is needed
 




snicklfritz

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if your cat is indeed going out it might help to check back pressure in the exhaust with a zero to 15 psi gauge you take an old o2 sensor hallow it out and put pipe to hose adapter on it pull front of cat o2 sensor one at a time and put your home made pressure gauge in o2 sensor hole should be a really low reading like 1 psi at idle and 2000 rpms no more then 3 psi. usually if a cat is going bad the are also plugging up another way is to take it to a smog shop the will test readings in front and behind cat but if your like me i just dont have money to use for something like that
 




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