Multiple engine fault codes after long drives

[NCunlimitedLJ]

Hey TJ Community,

First post, long time reader. I purchased the TJ in Fall 2019, and it has been great. My wife and I have done a few short road strips (2-4 hours) without issue.

In May, we took a trip to the OuterBanks (3 -4 hr drive) and about 2 hours in, the engine sputtered at highway speed and the check engine light came on. We nursed the TJ into a gas station in the middle of no where in Eastern NC and checked the codes. It was P0340 indicating a camshaft position sensor issue. At this point it was 9 PM at night, we were googling away and it appeared this was mostly an electrical gremlin. I located one thread that mentioned there was bundle of wires that rubbed against the back of the valve cover on the passenger side of the motor. In that instance the OP clearanced the bundle of wires from the engine and this seemed to help. Of course I did this, crank back up the TJ and debated for a minute returning and traveling back to Raleigh to grab another ride or continuing to the beach (at this point will outside the 100 mile free two from the AAA membership). With a quick Italian tune-up, I determined it was running great and continued on our trip. Ultimately we had a great trip, fishing for cobia, driving up to Corolla and going out on the beach to view the Wild Horses and the Jeep was great - no more issues.

Fast forward several weeks, heading to the beach again (not the OBX this time). About 3 hours into our trip, we are in a small town in South Carolina, and the jeep starts bucking, the check engine light comes on. The TJ stalls in the middle of the road etc. We eventually get it off the road, next to a NAPA - safe and out of the way.

I ran the codes and this time presented with:

- P0201
- P0340

Look up P0201 and see it indicates an injector issues with cylinder #1 — call around and no local place have any in stock. Wait about an hour and continue on journey and all seems well (30 minutes left).

Heading back home today - 2 hours in, the check engine lights come on. I noticed and exited off the interstate. Soon after the engine light comes on, the jeep sputters and stalls. Checking the engine codes, this time we have P0340, and P0508. This is another random code indicating something up with the IAC. Getting use to the drill, we were close to a Mexican food restaurant, so we hiked over, enjoyed some food and a beer. During this time did some googling and noticed someone put up the procedure to "reset" the PCM. We followed this process (unplug battery for 30 seconds, reconnect, turn key on, turn head lights off/on).

Started up the jeep and it seemed to run fine. It took us 45 minutes to get home but all was safe.

At this point it seems to be an issue that only occurs after 1.5-2 hours of driving. Since the engine codes seems to vary, I think this is either a PCM issue or a wiring issue — but seems odd it only occurs after a lengthy drive. Once the jeep cools down for an hour or so it seems fine. My wife and I drive the jeep often in and around town, and it seems fine. Does anyone have ideas as to what could be going on?

Btw the Jeep is a 2005 LJ with the Auto and 140K.

Apologies for the long message.

Thanks,
Jeremy

 

[CharlesHS]

Disconnect all 3 of the ECM 32 pin connectors and inspect the pins and terminals for dirt or oxidation.

 

[Goatman]

Could possibly be there are some wires in the bundle you moved that have worn thin or thru that may start to short each other when everything is good and hot under the hood? I try to always think of the easiest or dumbest way for a problem to occur and start there. It is normally something stupid in this type of situation than any major component meltdown.
Welcome to the forum. Tons of great info and tons of great guys/gals here to help you out.

 

[SkylinesSuck]

I agree the wiring harness sounds like the culprit.

 

[NCunlimitedLJ]

Thanks — did not get a chance to check out these great suggestions yesterday evening, but plan to do so tonight. Will start by checking the connectors on the PCM, then trace the wiring and see if I see any obvious wires that may be shorting out etc and report back.

Thanks
Jeremy

 

[NCunlimitedLJ]

Okay - so a quick update. I pulled all the connectors off the PCM and examined and they looked brand new. Starting tracing all wires, and as I touched the wire loom in many locations it crumbled (guessing that is simply a sign of a 15 year old Jeep). I do not see anything obvious on the passenger side.

Over on the driver side, there are two wires going to the brake proportioning valve under the brake booster that are clearly frayed and I could see them shorting against each other without too much effort. I examined these after cutting away much of the tape and the wires appear fully intact so for now I have simply wrapped in electrical tape.

I have attached some pictures to show the wires — hoping this addresses the issue, but regardless it was an issue that certainly needed addressing.

Next step - plan a 3-4 hour drive to confirm. Guessing a trip to the mountains of NC are in our future.

 

[SkylinesSuck]

Mine frayed in the main harness where it runs around the back of the valve cover against the head bolt. Probably worth checking out. Just letting it idle and jiggling the harness all over is probably worth doing.

 

[NCunlimitedLJ]

Thanks - I did leave running for approx 5 minutes and wiggle much of the harness, particularly where you are mentioning. In retrospect, I probably should have done the same prior to my quick fix.

 

[NCunlimitedLJ]

Hey Team,

The story continues - in the mid 90's today in NC and took the jeep out for some errands - maybe 60 minutes of driving total with 3 stops in between - did fine.

Came home and then my wife took the jeep to the grocery store maybe 10 minutes later. Less then a 10 minute drive. On the way back the check engine light popped on and she was able to limp it into the driveway where it turned off and would not immediately start.

A few minutes later it started and we checked the codes:

P0508 - IAC
P0032 - O2 sensor
P0038- O2 sensor
P0052 - O2 sensor
P0058 - O2 sensor

The last 4 are all additional random codes for the O2 sensors.

Last week the battery ended up dying on us, and in the process I noticed the negative battery terminal was cracked and not making proper contact. Ended up replacing the battery and the terminals with marine grade terminals. I had my fingers cross that maybe this had created some of the earlier issues but clearly not.

In reading some threads, I see recommendations of checking all ground straps so I will plan to do that. I am beginning to feel more and more that this is a PCM issue, and from checking wranglerfix.com the replacement pcm for an Auto is $573. This is almost at the point where a $600 gamble is worth it in the troubleshooting process.

Any feedback/thoughts? Also - for checking codes I have just been pulling from the odometer (turning key on/off 3 times). Would and OBD reader provide more info?


Thanks,
Jeremy

 

[taylormade73]

I would call Mark @Wranglerfix . He is pretty straightforward whether he believes it to be the PCM. He doesn't seem to try to sell everyone a PCM.

 

[glowell222]

I had this problem as well some years ago ('98 Sahara). Turns out that the upstream O2 sensor wiring had broken free from the wire tie and the insulation had melted against the exhaust manifold and left a large area with no insulation. My issues only happened during higher speed, and I am guessing that the higher speed wind would cause the wiring to flail around and eventually hit the manifold and cause a short. It wasn't easy to see that the wiring was melted-I found it after physically tracing the wires out by hand and feeling the bare wire.

If you end up needing new O2 sensors, be sure to use the NGK OEM sensors.

Generally speaking, with older cars and their electronics, these electronics and circuit boards are very well made and can stand up to a lot of abuse. What ends up failing (most of the time) are the capacitors on the boards. The capacitors eventually leak and fail (they are basically cylindrical containers) and this failure will cause the board to either fail completely or to have intermittent issues that are a nightmare to resolve.

 

[NCunlimitedLJ]

Thanks for the ideas - I sent an email to Mark @Wranglerfix to see what he thinks. Tonight I got under the jeep and thoroughly checked all O2 sensors and the wiring seems to be fine (for what that means to my untrained eyes).

During this, I noticed the ground strap going from the firewall to the hood is broken and no longer connected. Hard to believe I never noticed, but worth correcting. I just ordered replacement ground straps and will be replacing. I find it hard to believe that this could generate the issues I am seeing but certainly needs to be replaced. Just a pain that it takes some effort to generate the issue, but it looks like we should be in the mid 90s this weekend so should be an opportunity to test.

On another note, instead of really focusing on currently having an unreliable jeep and fixing that, I finally pulled the trigger on a lift. I have had new wheels/tires (33" Duratracs on 15" black alloys) sitting in the garage since May and have just been in information overload mode on the lift. Finally decided on the 4" Currie lift and paired with Ranch RS9000XL shocks. I may start a build thread on that, but definitely having a reputable shop in the area do the install based on a couple factors (work a ton, lazy, and generally always underestimating how long it takes me to do things). More to come on that.

Also realizing all my post fall under TLDR (too long, didn't read).

Thanks,

 

[NCunlimitedLJ]

Providing a quick update.

Replaced the ground strap going to the hood. Post that issues continue which I certainly expected.

In the last two days - the following codes have popped up which have included some fun times on the side of the road, resetting the PCM:


P0201 - cylinder 1 injector malfunction
P0508 - Idle air control valve circuit is low
P0032 - bank 1 O2 S1
P0038 - Bank 1 O2 S2 heating element high voltage
P0052 - bank 2 O2 S1
P0058 - Bank 2 O2 S2 heating element high voltage

Today's adventures included the speedometer bouncing from 65 to 0 and all over the place while on the interstate. A great precursor to cells popping and the jeep bucking etc and eventually stalling out.

I am leaning towards the PCM, but preferring not to replace and have an existing issue that creates issue with the replacement. I have also seen reports that failed precats and/or loose bolts on the exhaust manifold could create the issues with the O2 sensors - but I feel that only addresses some of the codes I have seen.

I have pinged a local Jeep focused shop to see if they could diagnose and point me in the correct direction.

Thanks,
Jeremy

 

[pagrey]

It looks like a wiring or ground issue to me. Unfortunately I don't know of an easy way to deal with it other than careful inspection of the harness and grounds. I have a feeling @Wranglerfix will suggest the same thing but obviously take his word on the subject over mine. The hood ground will not cause any issues even if it is removed.

 

[NCunlimitedLJ]

Okay — spent a while inspecting every wire I could find from the the engine harness to the O2 sensors, to the wires going to transmission and speedo gear. Could not find any shorts anywhere.

I did notice one bolt on the exhaust manifold to the precats was not extremely tight and addressed that and cleaned the 105 ground.

Took a few drives and could not break it. Convinced the wife to try to break it. It finally did this Friday - more error codes - same story.

A bit later Friday morning, called up Mark @Wranglerfix and I had a conversation with him like I have known him for years. That in my book goes a long way towards providing great customer service. Needless to say, placed my order minutes after disconnecting.

It may not fix all the problems I am seeing, but feel it is a step in the correct direction.

 

[Jerry Bransford]

Could be the PCM but when my TJ was generating random O2 related codes it turn out to have been caused by one of the small pre-catalytic converters. But those heater codes kinda make me think PCM since they are powered directly by the PCM on 05/06 TJs from what I can tell rather than the pair of relays used on older TJs.

 

[Wranglerfix]

Well, I became the proud owner of an 06 manual that I will getting tomorrow! It will used for pcm building and testing purposes as well as my daily driver

It currently has...

Dana 44 front and rear with ox selectable lockers. Chromoly shafts and 37s. 4.88 gears. Any suggestions on improvements will be greatly appreciated!

My investment in this Jeep is my commitment to you that we are here for the long run and will continue to build a product that performs as it should!

Thank you for your support and I look forward to hearing your suggestions!

Mark

 

[NCunlimitedLJ]

Hey Team - some quick updates.

Received the PCM from Mark @Wranglerfix Monday. It took approximately 10 business days from the time ordered which is what Mark advertises and came well packaged. I may or may not have bothered Mark during the short wait period.

The Jeep was at the shop for some other work (catch the build thread) so I took it over there and they installed the PCM. They called me less than an hour later and said it started and did fine on a 20 mile test drive.

Since then have driven it approximately 30 -40 miles and no issues. It is probably too soon to say it fixed the issues with this Jeep, but should know after a trip this weekend if we decide to take it.

I will provide future updates.

Thanks,

 

[Wranglerfix]

Thanks for letting us know and please keep us updated.

 

[NCunlimitedLJ]

Okay - about two weeks since last update. I have put 500 miles on the LJ since the PCM replacement from @Wranglerfix and I think** the issues are all resolved. Took a 115 mile trip and no issues on a hot NC summer day and no issue. Driving around town multiple times and and has not missed beat. Money well spent!