P0202 code but injector is okay

Blue Maltese

Blue Maltese

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Nov 17, 2016
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Surprise, AZ, United States
I accidentally wiggled the wire connector to my Cyl #2 fuel injector, before I noticed the wire insulation had dried and cracked, and the wires on the injector connector shorted against each other.

I got a P0202 code and the engine is running a little rough. I bought a new wire pigtail and soldered it on, but it wouldn't connect to the injector properly. I then checked the old connector I had cut off and it checked out OK, so I insulated the bare wires and soldered it back on. the connector fits good now. So I tested the ohm reading on cylinder #2 fuel injector and got nothing. I figured the fuel injector was bad. I removed the fuel rail and tested all the injectors while I had it on the workbench. They all showed 12 ohms; even the #2 one I thought was bad. I put everything back together and test drove the 2001 Jeep Wrangler 4.0 that I have 120,000 miles on. It still throws a P0202 code which I suppose needs to see an OK condition after several short trips before it resets. However my engine still runs rough and removing the wire connector while it's running doesn't change the idle roughness.
What do I do now?

The injector reads 12 ohms and the wiring connector checks out good.
 
Did you clear the code with a code reader or by resetting the battery?
 
Yes Chris. I unhooked the positive cable from the battery for about 10 minutes while I checked ohms. The CEL stayed clear for a few seconds after I started the Jeep, but then it came back. The check engine light was even flashing for awhile. I've never seen that before.
 
Blue Maltese said:
Yes Chris. I unhooked the positive cable from the battery for about 10 minutes while I checked ohms. The CEL stayed clear for a few seconds after I started the Jeep, but then it came back. The check engine light was even flashing for awhile. I've never seen that before.
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The CEL will flash if a severe misfire is detected that has the potential to damage the cats. Good rule of thumb is to shut it down if you see the CEL flashing unless you like spending money.

While I'm not sure how the Jeep ECM reacts, in many cases if a fault like this exists the ECM simply shuts down that injector until the problem is solved...which evidently, it isn't.

WIthout a scope, I would check continuity between the connector terminals between power and ground, and compare that reading to another cylinder who's injector is working. It's very possible that the short took out a driver in the ECM for #2, or that another short exists.
 
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I had a friend contact me and told me she had the problem and it turned out to be an engine bolt had rubbed through a wire causing the short. I'll look to see if my harness is shorted somewhere else. I'm not familiar with what a driver is in the ECM.
 
Blue Maltese said:
I had a friend contact me and told me she had the problem and it turned out to be an engine bolt had rubbed through a wire causing the short. I'll look to see if my harness is shorted somewhere else. I'm not familiar with what a driver is in the ECM.
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The driver is the transistor that turns the injector on and off.

Check continuity between power and ground on each terminal on both that injector and another cylinder. Then unplug the ECM and perform those test again. Depending on how they compare during both tests will give you a clue as to where the problem lies.
 
I'm having a similar issue with P0204.

After replacing all the injectors, checking wiring, etc... I'm now attempting to have SIA Electronics repair my PCM.

Planning on shipping them the PCM tomorrow... will let you know what ends up happening!
 
I was able to determine all the wiring was good. I checked pulse signal from PCM and there was no pulse signal. Now I'm checking to see if I can take apart the PCM and fix the problem myself....maybe a solder joint.....or if I need to get a replacement PCM.
I'll try to attach my wiring diagram that helped me figure stuff out.
Thanks everyone for your support.

fuel injector wiring.jpg
 
Very nice job with the diagnosis....

ECMs are not difficult to fix...just take your time and think about it.

Give it the sniff test first. 95% of the time if a component cooked to the point it no longer functions...you can smell it...smells like burning.

Your diagram shows 6 injector drivers...so look for 6 of the same components on the board...then get out a magnifying glass and give them a good inspection. You'll likely see the bad one blistered with possibly some burn marks on the board near one of the terminals or on an adjacent component. Find some numbers off of one of the other cylinder's injector drivers and google it....last one I needed (toyota ECM) I found for $027 with $7 shipping, but I was too cheap for that so I stole one out of a different ECM I had laying around. De-solder the old one, re-solder the new one...glue the box back together and you now have a "rebuilt" ECM for not much money and only a bit of effort.

Now, if you don't smell burning or see any cooked components...we need to rethink this...did the thing simply disable the injector when it saw the fault? I don't know the if a mopar PCM will do that or not, and I'm not sure how to wake it up again if it did.
 
I believe I shorted the tan and green wires together on the #2 injector pigtail connector. I was fiddling around with the insulation I had wrapped around the injector and didn't notice the insulation on the two wires had cracked and the wires were bare. I think I did this while the engine was running. I had just replaced the thermostat and was waiting for it to open and circulate. So I was putzing around as I waited. So I probably shot a 12volt short into the #2 driver of the PCM. I'm looking into replacing the PCM and finding out the VIN needs to be programmed into it. Sounds like I better just buy one rather than try to fix my own. I found one for $525 at Flagship One. OUCH!!
 
Blue Maltese said:
I believe I shorted the tan and green wires together on the #2 injector pigtail connector. I was fiddling around with the insulation I had wrapped around the injector and didn't notice the insulation on the two wires had cracked and the wires were bare. I think I did this while the engine was running. I had just replaced the thermostat and was waiting for it to open and circulate. So I was putzing around as I waited. So I probably shot a 12volt short into the #2 driver of the PCM. I'm looking into replacing the PCM and finding out the VIN needs to be programmed into it. Sounds like I better just buy one rather than try to fix my own. I found one for $525 at Flagship One. OUCH!!
Click to expand...

That'll learn you to putz with stuff....putz.

Don't replace the PCM...fix it. It's easy, and if you simply replace the thing you fucked up, it'll cost you less than lunch, and it won't need any programming
 
Update on my previous post.

Just got the repaired PCM back from SIA Electronics after a very quick two-week turnaround.

After sitting idle for two weeks in the winter cold, my Jeep starts up immediately with the repaired PCM and check engine light has disappeared!

Fingers crossed that this issue has been resolved! 🤞
 
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Clintryan said:
I’m having the same problem on mine but it’s #2&#4 smh
Click to expand...
Before you rush to do what I did (send out the PCM for repair), go through the steps... swap some injectors around and see if the codes change to different locations. Check the wiring harnesses to the injectors...
 
Apologies for reviving an old thread, but after hours of searching various sites and threads, I keep coming back to this one because it seems like I am having potentially the same issue. 2006 LJ 4.0 automatic with 175k threw a P0302 and P0202 code the other day. I've owned the jeep for about 40k miles so pulled and replaced the plugs with new Autolite XP985s, cleared codes and restarted. P0202 popped back up immediately and the P0302 shortly after. Listened to all the injectors (screwdriver stethoscope) and #2 clearly is not working. Checked ohms on all 6 and they are all consistent leading me to believe that the specific injector is not the problem. Following Blue Maltese's post above, I checked the wiring harness for wear and found nothing that would indicate a possible break or short, even at the contact point behind the valve cover where it commonly occurs. Next thing I attempted to do is check the ohms between the PCM and the specific injector as stated above, but am not well versed when it comes to wiring and am not sure I am testing it correctly. Can anyone explain how I would test that circuit? Do I connect the multimeter leads to the two female sides of the wiring connector for that injector? When I do, I get 0 ohms which could be a good thing, or could mean I'm not testing it correctly.

Thanks for any help anyone can provide.
 
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The 05 and 06 TJs had endemic PCM issues.

Did you ever get yours repaired by someone like wranglerfix.com @Wranglerfix ?

If nothing else you can send your PCM in for testing and eliminate it as the cause of the issue.

Have you moved/swapped injector 2 to another spot? See if it misbehaves in 3.

I bought a rebuilt set of Siemens injectors for my 97 from Precision Auto Injector and was very happy with their service.

-Mac
 
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