UPDATE: CEL & Codes: O2 Sensor Heater Circuit Malfunction

Hey folks received these codes for the 2nd time after clearing them once p0135/p0141/p0155/p0161 after approximately a dozen start-run cycles. Seems to be pointing at needing to replace the precatalytic exhaust assembly since all 4 O2 sensors failing at once seems unlikely. There are mentions of damage to the wiring harness as a potential cause for this condition and a TSB that addresses the matter if no damage/faulted parts are identified: https://www.tsbsearch.com/Jeep/25-005-13-REV-A .

06 LJ, 6spd, 111,000 mi, 2nd owner of 14yrs, no perceived performance or gas mileage degradation, runs well, this is my daily driver with minimal off-roading beyond 2 tracks surfaces or the beaches of COROVA.

Any insights or recommendations are very much appreciated.

Happy Holidays!
 
Those are all o2 Heater circuit malfunctions...

This is gonna sound strange, but if they all popped up at the same time, I'd be looking for a power problem, Not an emissions problem.

Make sure the battery has a good charge, and the cables are tight.

Make sure all the grounds around the engine compartment are good.

Check resistance between the engine block and the battery negative post.

If all that checks out good, Then I'd move on to harness that goes to the oxygen sensors, but if you aren't getting any other emissions codes, I doubt its that..
 
  • Like
Reactions: R3
Those are all o2 Heater circuit malfunctions...

This is gonna sound strange, but if they all popped up at the same time, I'd be looking for a power problem, Not an emissions problem.

Make sure the battery has a good charge, and the cables are tight.

Make sure all the grounds around the engine compartment are good.

Check resistance between the engine block and the battery negative post.

If all that checks out good, Then I'd move on to harness that goes to the oxygen sensors, but if you aren't getting any other emissions codes, I doubt its that..
Interesting, a few weeks ago during a normal under hood "look around" I found the grounding strap from the hood to the valve cover corroded and broke. I cut out the bad section, terminated a new connector and bolted it back to the hood in a new spot since it became a couple of inches shorter. I know it's one leg of a "3 leg'd" grounding strap the other leg coming off the rear of the engine block which appeared secure at a glance, I'll have to take a closer look and check the resistance and remaining grounds as you've suggested. I did want to replace the entire grounding strap rather than repair it but I was unable to source an OEM part anywhere and best alternative was to build my own, so I figured I'd just repair the leg that was corroded.
So I have to wonder if my after market sub-woofer which has been working well for years and just recently started cutting in and out is related? I troubleshot that for a few hours a month or so ago and w/ Crutchfield's tech support on the phone we'd isolated the issue to the head unit.....hmmm!
 
The subwoofer has an amp built into it? If so, yeah I can see that being affected by grounds too, especially if you grounded it to the body close to the Sub itself.

There's no reason not to add an extra grounding strap or three between the body, frame, and engine block... I do that when my older vehicles start to have electrical gremlins...

One of these Dorman Grounding Straps near a body mount from the frame to the body floor, one from a frame side bolt to an engine side bolt on one of the motor mounts, and one from an intake manifold bolt to the firewall. All of those in addition too, not replacing, the existing ground straps has gone a long way for me in saving headaches...
 
  • Like
Reactions: R3
The subwoofer has an amp built into it? If so, yeah I can see that being affected by grounds too, especially if you grounded it to the body close to the Sub itself.

There's no reason not to add an extra grounding strap or three between the body, frame, and engine block... I do that when my older vehicles start to have electrical gremlins...

One of these Dorman Grounding Straps near a body mount from the frame to the body floor, one from a frame side bolt to an engine side bolt on one of the motor mounts, and one from an intake manifold bolt to the firewall. All of those in addition too, not replacing, the existing ground straps has gone a long way for me in saving headaches...
Yes, it is a powered sub, thanks for the suggestions once the temps warm just a bit I'll get to it. In the meantime I'll order some straps. (y)
 
So, almost a year later I think I may have finally slayed this dragon.
Replaced the ground straps as suggested but the problem persisted...ended up stumbling on a thread on another forum that pointed to G105 grounding point as a possible culprit. Lo and behold, the ground is secured via a threaded stud into the block and it secures the battery ground and the 4 ground wires for the 4 o2 sensors! Unfortunately I couldn't disassemble it as it was loose and I couldn't get tools on it to hold the stud and break the nut loose so I cleaned it up and firmly albeit judiciously tightened it back up avoiding too much to torque so as not to snap it. Cleared the codes and rolling through a full cycle watching for recurrence of the CELs but the sub has NOT cut out once since the "repair".
Fingers crossed it holds...I think we got it, time will tell.

Thanks all for the input.

00acc591-ccee-478a-88e0-e959a239369a-png.106096
 
What's shaking Adam? Hope all is well, been a minute!
Pretty much same old same old, getting old. I get on here from time to time and help when I can though the latest TJ's being close to 20 years old means I can't add much, and makes me feel older 🤣 Kids are growing up, oldest is in middle school now. Took a remote job several years ago and have been enjoying it, infinitely better life balance than the commute from Loudoun to Fort Detrick I did daily for 5 years. Much more time with the kids during these especially important years and I have the opportunity to balance out the load my wife was previously shouldering. Usual bumps in the road time to time, but overall life is good.

How are things with you?
 
Last edited:
All good news, very happy to see you and the family are thriving. Our girls are both married, the oldest 2021, the youngest was married last month so now the countdown to corrupting any grandkids that happen along begins. I'm working for Oracle now, been fully remote since about 2015, the kids insist it's made me feral, HA! I just can't seem to let this LJ go, nothing on the newer or new market intrigues me, too many "Nanny" features for my taste though I could be coaxed into an Alfa Romeo Giulia in Quadrifoglio trim 🤤!

I'm sorry to report, after several days the sub cut out again even though the G105 ground remains secured. No CELs yet but I suspect it's just a matter of time before they return as well. The search for a cure continues.

1930PM ET
The codes are back p0135/p0155 this time....
 
Last edited:
Good stuff - no more weddings to worry about should mean more Jeep funds and time! 😉

Did you complete the TSB you linked above? Reading it shows it's the ASD relay which can cause all sorts of wonky issues. If you troubleshot the aftermarket subwoofer down to the head unit, I'm assuming it could be the head unit/remote turn on like Crutchfield said if the ASD relay gets finicky and blips out. Would also explain why the O2 sensors set themselves back the 50 miles of driving before stating ready.

Generally ASD issues will kill everything but the TSB mentioning only O2 sensor readiness concerns makes me think it may be blipping out too fast or not fully, dropping voltage and only certain systems are picking this up. I'm assuming the sub is directly grounded to the body/frame through a seat or roll bar bolt, so really the only two things that would cause it to blip would be lack of remote turn on or ground. If you've dealt with the body grounds, seems that it's a power supply concern.

Edit - just read the p0135/p0155. To my knowledge, the heater circuit on these Jeeps is controlled via 12+ switching, not ground. This would throw more focus on the ASD relay. Also saw WranglerFix in multiple threads regarding related codes, you're a thorough guy so I'm guessing you saw this as well, but worth a call and chat if not already done.
 
Last edited:
The TSB is not something I'm in a hurry to try...even in official Mopar letterhead seems like a damn kluge to me but folks have had success with implementing it.

I went over the all the sub wiring and grounds again, everything looks solid.

Interesting note on the 12+ switching, will throw an eye at the ASD Relay circuit...which will likely bring me back to the TSB.

Stay tuned!

PS, I did find the PCM replacement at WranglerFix in my journeys, would love to not start throwing parts at it but might be the solution.

For the record, I replaced the battery about 3 months ago.
 
Last edited:
The TSB is not something I'm in a hurry to try...even in official Mopar letterhead seems like a damn kluge to me but folks have had success with implementing it.

I went over the all the sub wiring and grounds again, everything looks solid.

Interesting note on the 12+ switching, will throw an eye at the ASD Relay circuit...which will likely bring me back to the TSB.

Stay tuned!

PS, I did find the PCM replacement at WranglerFix in my journeys, would love to not start throwing parts at it but might be the solution.

For the record, I replaced the battery about 3 months ago.
I have an 06 LJ 6mt that kept throwing multiple o2 related codes. I replaced the catted downpipe and all of the 02 sensors without luck. Eventually I ended up talking to mark at WranglerFix. I was hesitant to spend the ~$1k on a pcm for a vehicle with no drivability issues, but I live in an emissions county, so I had little choice. He was very thorough and confident that it was the PCM, even going as far as to tell me he'd refund my money if it didn't fix the problem. Well, 7k miles later, the codes have never come back. Its worth giving him a call. Great company, great guy.
 
I have an 06 LJ 6mt that kept throwing multiple o2 related codes. I replaced the catted downpipe and all of the 02 sensors without luck. Eventually I ended up talking to mark at WranglerFix. I was hesitant to spend the ~$1k on a pcm for a vehicle with no drivability issues, but I live in an emissions county, so I had little choice. He was very thorough and confident that it was the PCM, even going as far as to tell me he'd refund my money if it didn't fix the problem. Well, 7k miles later, the codes have never come back. Its worth giving him a call. Great company, great guy.
Since my last post I've been reading WF customer posts in other forums and watching the WranglerFix videos which make it feel they're a quality outfit with a thoughtful approach to managing these elusive CEL issues having put a lot of R&D into the matter. Thanks for sharing your experience, I'll be starting a dialogue w/ WranglerFix shortly to see what they recommend.
 
Since my last post I've been reading WF customer posts in other forums and watching the WranglerFix videos which make it feel they're a quality outfit with a thoughtful approach to managing these elusive CEL issues having put a lot of R&D into the matter. Thanks for sharing your experience, I'll be starting a dialogue w/ WranglerFix shortly to see what they recommend.
Mark was nothing short of impressive when I spoke with him. I have had no functional issues with my replacement PCM, but it does show a stored code for a faulty SKIM (secure key). My jeep wasn't optioned with SKIM and it doesn't trigger a CEL, so i never brought the issue up with Mark. You'd only ever know about it existing if you pulled diagnostic codes. I'm assuming it was harvested from a vehicle that did have SKIM and that's why its there, but I only mention it in case you do move forward with WranglerFix.
 
Back
Top