Codes P0137 and P0138

[wonderlandsfinest]

Hi guys! I'm new to the forum and hoping that some of you more experienced Jeep lovers might be able to offer me some advice. I love my Jeep and want to get it back into tip top shape asap!

About three months ago, I noticed a strange smell when I was driving my jeep. At first I thought it was just my imagination or surroundings. But over time I realized that it was in fact a rather distinct smell of burning plastic or rubber. The smell I've come to realize is more prominent when I have the air or more specifically the heat on. When I had a friend check, they accounted the smell to the serpentine belt and changed it for me. But the smell persisted and a few weeks ago the check engine light started to go on and off(it would be on when I drove sometimes and then disappear during other trips only to reappear a few days later).

So I took it to an autoparts place and had them scan it, at which point I was given the codes P0137 and P0138, which I googled and read several articles on. It seems like the most common cause of these codes is the oxygen sensor but considering the smell, I thought that perhaps it had to do with an exhaust leak. So I took it to a shop that would check the muffler system for free(because I'm a poor **** and can't afford to throw $100 at a mechanic just to tell me what's wrong with my Jeep) and they said that they couldn't find any problems with the exhaust. They suggested it might be the catalytic converter because of the smell but described the smell from that as something similar to rotten eggs(but of course they didn't check that and want to charge the $100 to do so). This is definitely not rotten eggs, it's burnt rubber/plastic.

The Jeep is still running smoothly(I drive it about five miles back and forth to work about three times a week and not much otherwise) aside from the smell and the light but I'd like to figure this out and fix it before that changes. I've also considered the possibility that the smell and the light are stemming from two different sources. Is that possible or just my wishful thinking?

So after that lengthy explanation, does anyone have any thoughts on the problem or advice? I'd really prefer to know what the issue is before I take it anywhere so I can have an idea about what I should be paying to fix the problem. Do I just need to suck it up and pay the mechanics to tell me what's wrong and go from there? Thanks so much for reading and I look forward to hearing your thoughts!

 

[MarkJ]

Is your Jeep undercoated?

 

[ltd02]

The smell is the tricky part. I see what MarkJ is saying. Something may be getting hot under there. That said and since you already read up on the code and they are both for the Dside downstream and contradictory you may want to check the wiring for that sensor very carefully. Make sure that ain't what's cooking. Other than that it may just be on its way out and easiest to just change it (NTK or Mopar).

 

[MarkJ]

I have see a Cat get so hot that undercoating on a crossmember 8 or 10 inches above was running off like oil into a smelly puddle on the ground. (in this case it was a chevy pickup with the timing way off...)

 

[ltd02]

I have see a Cat get so hot that undercoating on a crossmember 8 or 10 inches above was running off like oil into a smelly puddle on the ground. (in this case it was a chevy pickup with the timing way off...)

Yep those things can get hot. Many years ago I had a 75 Ford Granada with a 302 and cooked the cat. The thing was glowing orange in the daylight and the carpet started to burn. Cut the whole system off and ran a straight pipe from the Y to a little tiny Thrush. Wouldn't recommend it now but sure made some fun noise back when I was young.

 

[wonderlandsfinest]

The smell is the tricky part. I see what MarkJ is saying. Something may be getting hot under there. That said and since you already read up on the code and they are both for the Dside downstream and contradictory you may want to check the wiring for that sensor very carefully. Make sure that ain't what's cooking. Other than that it may just be on its way out and easiest to just change it (NTK or Mopar).

What do you mean when you say it's on its way out? The catalytic converter? Not the whole Jeep I hope! It's only a 2004 with less than 125k miles on it and I've been pretty gentle with it in the three years that I've had it. I did have a pair of deer hop out on me last year though and they ended up banging up the underside of the Jeep. Insurance paid for repairs but maybe they missed something?

I'm not sure about undercoating though. How would I check about that?

Thank you all for your thoughts! Now I've got a few more ideas on what I should be investigating.

 

[MarkJ]

I think he is talking about the catalytic converter, not your whole Jeep. Although, usually when converters age they get less efficient, they usually don't get hotter. Converters get hot from another reason, usually a too rich mixture. I suppose this may happen if the converter is telling your engine that it is running too lean. Your point about running over deer makes sense and could be a factor. Need to get under it and identify and check all the cats and 02 sensors. Check all the wiring and make sure the deer didn't damage anything or anything is hanging down in a wrong place. This could also be related to cat wires themselves getting out of place and touching a hot pipe and melting. The undercoat is a tar-like substance that is sometimes sprayed on all the metal body (not running gear or exhaust) under a car to help prevent corrosion and also deaden road noise. It will react to an overheating converter by at least giving off a burning rubber type smell. Again, I would give your Jeep's underside a thorough inspection. Question everything.

 

[ltd02]

I think he is talking about the catalytic converter, not your whole Jeep. Although, usually when converters age they get less efficient, they usually don't get hotter. Converters get hot from another reason, usually a too rich mixture. I suppose this may happen if the converter is telling your engine that it is running too lean. Your point about running over deer makes sense and could be a factor. Need to get under it and identify and check all the cats and 02 sensors. Check all the wiring and make sure the deer didn't damage anything or anything is hanging down in a wrong place. This could also be related to cat wires themselves getting out of place and touching a hot pipe and melting. The undercoat is a tar-like substance that is sometimes sprayed on all the metal body (not running gear or exhaust) under a car to help prevent corrosion and also deaden road noise. It will react to an overheating converter by at least giving off a burning rubber type smell. Again, I would give your Jeep's underside a thorough inspection. Question everything.

X2 Yes, I just meant the O2 sensor may be failing or "on it's way out". They can fail. I just replaced one on my 2011 avenger that failed with only 58k on it. As stated above, you definitely need to get under there (safely) and have a look around. Check the clearances around the entire exhaust system and check the O2 sensor wires while you are at it. Make sure the exhaust didn't get bent up into the body too.

Undercoating is usually a thick textured black rubbery coating. Mine is not undercoated and surfaces are smooth and hard. Like MarkJ said, see if there are any areas around the exhaust that may be melting and dripping on the exhaust.

 

[wonderlandsfinest]

Again, thanks so much for your input guys! I'll have to see if my mechanic friend can be convinced to check the underside of the Jeep.

This morning when I got home from work, I popped the hood and took a look inside. The smell seems to be coming from the front/leftish area from what I can tell. I tried to look at all the wiring as best I could from above and did find something that looks a little strange. The bar beneath the serpentine belt(forgive my limited vocabulary, I'm learning what everything is as I go along) had some gritty black **** for lack of a better word on it toward the right side and one of the wires/tubes/whatever it is above it also looked like it had some on it. It's greasy to the touch and almost looks like it's dripped down from somewhere but I'm not sure of the source. I did snap a few pictures of what I saw though.

I tried to get the camera down as close as possible but it was hard to get a good picture of the gunk on the bar because the engine was still hot but I think I got the jist of it here.

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The cable in the front of this picture is the one that looks like it has a similar substance on it.

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And in this one, the cable farthest back has the gunk all over where it connects into whatever that is it's connecting into. Is it suppose to look that grimy or could this have something to do with my troubles?

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[uss2defiant]

All that gunk is caused by leaking ATF+4 or PS fluid. The hoses that have a film over them are the PS hoses. From the last picture, the high pressure side hoses are leaking. I can't positively say whether the Low pressure side is leaking too from your pictures but it is best to replace them all.

Not related to the codes you pulled out.