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How To: Pull Trouble Codes on a 1st Gen Explorer (paperclip method)

I'd start with a wiring diagram. As frequently as these sensors fail, I'd check for shorts/opens between the sensor and the PCM. If that all checks out, then I'd replace the DPFE/PFE sensor.

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Anyone know what to do if it refuses to show codes? my cel works it just don't do anything when I attach the paper clip.

The first question I would ask is if it entered test mode or not. Does the CEL go off when you initiate the test (indicates that it does enter the test) or does it stay on (indicates that it didn't enter the test)? Can you hear the relays click indicating that it entered the test? If you hook up a voltmeter to the self-test connector output (see the diagrams in Brooklyn Bay's EEC-IV code list thread), does it output codes?

The cel just stays on as if I hadn't connected anything. The cel isn't on when the car is running but I KNOW the engine isn't running well.

I don't actually have a voltmeter they're expensive.

The cel just stays on as if I hadn't connected anything. The cel isn't on when the car is running but I KNOW the engine isn't running well.

I don't actually have a voltmeter they're expensive.

Digital Volt meters are cheap too. I pay < $3 for them (at Harbor Freight) and I throw them away when its time for a new battery. When they aren't on sale they are still < $10 each.

You don't need anything fancy.

For testing the CEL an analog meter is easier and I know I paid well under $20 for it.
Cheap analog one from amazon.


I have a digital that I got at Sears on sale for $19.99

That's kind of one of those tools that if you're going to work on your vehicle a fair amount, you just have to have one- they're way too valuable to not have.

Not well understood

Hello everyone,

:banghead: I just read the thread, but with the translator is not easy to understand everything.
The threadl explains how to find a flaw and its code number?
I'm sorry and apologize for boring you :dunno:
But here in France, nobody knows how to work on Ford Explorer
I take all the interesting information for me and then I made a French translation to do my own repair manual


The cel just stays on as if I hadn't connected anything.
That suggests to me that it isn't entering test mode. Make sure you are jumpering the correct leads, make sure you are getting a good connection on your jumper wire. If that doesn't get it to enter test mode, check the wiring between the test connector and the PCM. I would bet that most of the time this is because you are aren't getting a good connection on your jumper.

HELP! Needing "De-coded"

Hey guys,
Your articles about the trouble codes really helped me understand the problem with my 93 Explorer. (See my post "Transmission or Brakes?")
Come to find out, using your paperclip method, it was neither of those.
Maybe you can help me figure out what it is exactly by decifering the codes it brought up:


Then the FIRST code came up as 522. Which I could not find a reference to. Could someone PLEASE help me figure out what I have to replace? I know the H20s is one, but what is causing the voltage change in the TP?
Come to find out, after wiping the codes, that this is what was causing the "surging" in the truck. (Glad to find out it wasn't the tranny!!)
Thanks, guys, you saved me a crap load of work!

122 Throttle Position Sensor (TPS) below minimum voltage
- Do TPS Test

124 Throttle Position Sensor (TPS) voltage above normal
- Same test

125 Throttle Position Sensor (TPS) voltage below normal
- Same test

175 HEGO (HO2S) Sensor fault not switching

176 HEGO (HO2S) Sensor fault/always lean

Suggested course of action:
Diagnose and repair TPS problem first. Then, clear codes and drive. Test again. It is possible the TPS problem is causing the O2 sensor fault.

For further diagnostics, please create a new thread, otherwise this one gets too big.

Hi guys
I did this test today and i am coming with 176 fault.
Can you help me what i need to check or replace.
Check engine light is coming when engine is running for more then 10-15 minutes.
On short distance never.

176 means the left (driver side) O2 sensor is reporting a lean condition.

On a 93, that could be an intake manifold leak. You can read plenty about lower intake gaskets, there are many threads on this. Engine running, I would take a can of carb cleaner, and spray it around the gasket from the lower intake to the left head and see if you get any idle change. If so, then you can try torquing the bolts, or worse case, replacing the lower intake gasket. Good notes on doing this, go to the Stock 1991-1994 section and search on lower intake.

Other possibilities... clean the mass airflow sensor, that's never a bad idea and it would cause lean, albiet on both sides, but maybe the left side is more sensitive. There are discussions about bad cat converters, coil packs, or it could be the O2 sensor itself. To address that, you can swap the O2 sensors left and right and see if the code changes.

Search the entire board for 'code 176' and you will get plenty of ideas. If you go much deeper on this, I would start a new post in Stock 1991-1994. You will get more visibility from people who know this engine.

Ok, so recently we've had a lot of questions about how to do this. MrShorty has a great How To on this already but it seems it's a little advanced for some people, so I'm going to make a simple "How To" with pics. This isn't a full how too, this is just to get you started, for the advanced stuff I'm going to link to MrShorty's post!!

----There is now also a video at the bottom of this post made by our own Joe Dirt, it details the process as well. So if you like video over pictures, or are still unsure, check it out!!!!----

*** This should work on 1st Gen 91-94 Explorers and also 95 2nd Gen. The 95 got a face lift but uses the same 1st Gen brain. From what I read if you have a 96+ you HAVE to have a code reader.****

So you've got a CEL light that likes to wink at ya, and you don't have a code reader!!! NO PROBLEM! All you need is a paper clip (or a bit of wire), your keys, your eyes, and your Check Engine Light.

First you have to locate your EEC test harness... It's back behind the Power Dist box on my 93...I've heard it's on the other side on some 1st gens, so I'm hoping someone will post up some pics for those models. It's the black box to the left of the air box in this picture...

What your looking for is a harness that plugged into the EEC TEST holder attached to the back of that black box. You pull the harness DOWN out of the holder, the holder stays attached to the Power Dist box. If the harness isn't in the holder (I don't put mine back) then it's laying loose just right behind this box.

Now this is what the harness your looking for looks like, you need both the black large one, and the single gray one....

You'll need a paper clip, or do like I do and use a piece of wire....

Now your going to "jump" the #2 slot in the main harness with the single gray harness like so...

Now you just get in the truck, turn the key, and watch this thing flash the codes at ya....

That's it, your done, and you now can get your Check Engine Light Codes from your 1st gen Explorer.

***Word of advise/warning... pulling the jumper off while the key is on (test mode) will erase all memory of all codes from the system. It's the same as leaving the battery unhooked to clear the codes. Don't pull the jumper during the test unless erasing the codes is what you are trying to do. It won't damage anything really, and is how I clear MY codes. Just be aware you'll lose your codes if you pull it during the test.****

I'm going to go over this REAL fast, then link you to MrShorty's post for the real deal. This is the process for the KOEO test (Key On, Engine Off). Get a piece of paper and a pen, make sure your jumper is in place, turn the key to "on" but DON'T start the truck. You'll start hearing some relays clicking and the fuel pump whine and after a few moments your CEL will "flicker" that's the "fast codes" out putting, those are for code readers and you ignore that "flicker". Then the real codes will start. The first codes will be any faults that are happening while the Key is on, but the engine is off. For example if you had a 157 fault from the MAF for example the CEL would flash once....*small pause* Five times *small pause* Seven times *small pause*, then repeat a second time (157). If you had two codes like 157 AND 158 it would flash both codes the repeat them both (157,158,157,158).

After the last code it will pause about *6 seconds* then flash once to tell you it's getting ready to give you the CM Codes. (that one flash is called the seperator flash) These are the codes that get thrown while driving but go away. In other words, if your driving and the CEL comes on, then goes off, this it where you retrieve that code. It will process just like above.

You will only get codes in the first part of the output phase (before the CM codes) if there is a CURRENT KEY ON FAULT, other wise you will get 111, that means everything is "ok" with just the key on, no faults the CPU could find. It will repeat just like normal codes. So lets say there are no current faults, but that the MAF went "high" while driving (158), this is what will be output... *flicker fast codes* (start of KOEO codes) 111,111 *6 second pause* 1 (seperator flash) *another pause* (start of CM codes) 158, then a repeat of 158, then no more flashes.

It takes some practice to get used to. But it's easy once you've done it. Just use a piece of paper and copy each code as it flashes, then figure out what you've got once you finish.

Ok, so here is the advanced instruction, and more general info on how to read the codes, and also how to do the KOER (Key On, Engine Running) test.

MrShorty's awsome thread about pulling codes!

And here is a link to what the codes MEAN!

Brooklynbay's list of OBD I CEL codes!

Here is a great video about how to do this made by our own Joe Dirt, enjoy!!!!

:thumbsup: I am yet another time that day
I tried to do with your very good explanation ...... (damage for Mister shorty I do not understand English ......)
But I must be somewhere in the procedural error because I can not do it.
I will redo this with a friend who understand English.
in any case thank you for writing this it is very good


OMG thank you so much! I've had the CEL off and on for about a month. I'm losing power on hills, hard starting, rough idling....etc. I remember my '94 Acclaim could output the codes through the ignition and it was great. Now my beloved Explorer can talk to me too!!! You guys rock!!!!

I must say this easier than asking autozone, does anyone know where i can get an obd-1 reader?

Most odb-1 readers just flash the codes to you. They are really just very fancy paper clips that make sound (so you can count without looking).

Autozone sells that kind. Its Part # CP9015 and is $29.99

The Equus Innova - Digital Code Reader Part # 3145 actually displays the numbers. That one is $32 at Oreillys (used to be CSK/Checker/Kragen etc). BUT, I found it on amazon for $22.


I have a 1994 Ranger XLT, 2.3L (200542.1 miles). You guys keep it simple, lol, and being the simple person that I am, I appreciate it. I was having a problem with the Ignition Control Module (ICM). It acted as though the coil packs were bad. After watching MrShorty's Video, I managed to pull the codes (seriously simple process). The codes indicated coils (both of em) were bad. On my way to work, the truck decided it was time to quit. Fortunately I was going by Auto Zone in Leland, NC and managed to roll into their parking lot at 7 AM. By 7:15 I was in the door and with Leslie and Angelo's help, determined that the coil packs were fine and the ICM was bad. Leslie did the test on their machine. I replace the ICM ( my right arm is still skinned up) and now my truck is running like a Swiss Watch. After talking to my cousin, I found that the check engine light had been on for years, and now it is gone. This is a GREAT FORUM !!!!! As we say in the US Navy......Bravo Zulu to Doonz, Joe Dirt, MrShorty, and Auto Zone's Leslie and Angelo. Thanks ya'll, I am now a Happy Camper.

Wonder if i can do same on a 96. Bookmarked thread just in case

Wonder if i can do same on a 96. Bookmarked thread just in case

Short answer:no

you have odb-II and rewuire a code reader or scanner


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Darn. No parts stores I go to will check OBD II anymore. However, they will sell me a scanner for bookoo dollars. No thanks, I'll do it the old fashioned way and replace all O2 sensors, unplug batt for awhile and see what happens. They are original equipment, so it's prob time to replace anyhow.