Check Engine Light On - Code P0038

[grogiefrog]

Tonight right after filing up the gas tank I had a check engine light come on. Before I got home, I went ahead and made sure that the gas cap was on tight (obvious thing to check!), and it was.

Once home, I tried to read the codes on my '04. I've never been able to get any codes by the fist two methods here:
http://www.jeepkj.com/forums/viewtopic.php?p=2227#2227

So I did some searching around and found that on "older" Jeep models to try this method to get the codes, which worked!
Start with the ignition off. Within five seconds, switch the key on, off, on, off, on. ("On" is NOT "Start" and "Off" is NOT "Lock").

Note I did add this to the link above as a third option.

Anyway, the P0038 code means "02 Sensor Heater Control Circuit High (Bank 1 Sensor 2) : Shorted condition detected in the oxygen sensor heater element control feedback sense circuit." I did a search here at JeepKJ.com and Talon on 6/22/05 reported this code and followed up by saying, "Update 8/8/05: I had the dealership look at it and they stated on their report: Tech found 02 Sensor not staying centered. Replaced 02 Sensor assy. Fixed under warranty."

For fun, I opened up the '03 Liberty Shop Manual I have (thanks to Tim!), and it's under "oxygen sensor heater element", it talks about the fuel pump relay terminals! Ah! And this happened right after getting fuel, so maybe it is "fuel" related?! Funny thing is, you know how the low fuel light always comes on when it's got about 3.5 gallons left? We'll I let it go to almost 2 (which my wife hates me to do), and my wife told me that I just waited too long to put fuel in it! LOL

So what does this all mean?! I guess she'll need to go visit the dealer soon, although I don't have time this week so it will have to wait. I'll update this then...

 

[MoladoGuy]

Okay. I know this code is different but it deals with the Oxygen Sensor located at the same location (Bank: 1 Sensor: 2).

My error code was: P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2

I checked and it was indeed the O2 sensor located right under the drivers side door. The problem was that the O2 sensor cord was rubbing against my drive train. I got it all fixed up and had no more issues. Not to say yours is the same problem but just stick your head under there and check out the cord/sensor.

 

[2003KJ]

Ohh boy, o2 sensor issues! Been chasing one on my neighbor's XJ for damn near a year now!

Sensor number 2 is really not important....strike that....not AS important. Sensor number 1 controls your air/fuel mixture and sends all the signals to the computer. Sensor #2's purpose is to monitor the Catalytic Converter, and make sure it's doing it's job and performing with in specs. The heater's are on them to get the sensor's up to temp quick, and i mean extremely quick.....they've gotta get hot way before the exhaust does so they function properly. So if you have issues with #2, generally wouln't experience any noticeable change such as engine running rich or lean, bad gas milage, etc. Everything will apear to act perfectly normal, unless you're Converter is shot, in which case you'll know....but this isn't your problem.

If I were you, unhook the battery for about 10-20 minutes to reset the computer (not the proper way to do it, but since you don't have a scanner it'll have to work for now), and drive it around like normal to see if it comes back on.

How long after filling up did the light come on? Too bad I don't live closer to you, i'd clear the computer with my scanner for ya and help you solve the issue. I think it's safe to say you're out of warranty? If so, I don't think i'd take it to the dealer. o2 sensor's are pretty straight forward to replace, and seeing as how your KJ isn't really that old, it shouldn't be too terribly stuck on the exhaust pipe if you end up having to replace it.

After reading Phil's post, i seem to recall atleast one other person I believe who had their o2 sensor #2 rubbing against the drive shaft and it shorted out. Definately crawl under the Jeep and have a look see.

Almost forgot to mention, alot of times with the #2 sensor, after a few start up's where the computer does not detect a problem, the CEL will go off by it self (however the code will remain on the computer's memory untill cleared by a scanner). This is what i've been chasing on my neighbor's XJ since March. CEL comes on for P0138, o2 sensor #2 voltage high. Every time i check that sensor with very expensive scanning equipment nothing is wrong, all is in spec. If i leave it alone the light will go off in a day or two, or sometimes even the same day. Gotta love Jeeps!

 

[grogiefrog]

Thanks for the info. guys. The light came on right after fill up. It made me stop and check to see if I had left the gas cap off! (biggrin)

Actually I am still under warranty until the end of May, so I'll take it in next week and let you know.

P.S. It's amazing that a modern vehicle runs as well as they do with all the electronics and parts!

 

[2003KJ]

So is the light still on? You might wanna see if you can keep the light on when you visit the dealer, otherwise they'll claim "nothing is wrong with it."

 

[grogiefrog]

Tim, I just went to UPS... started it up and no light. So I guess I won't be taking it in unless it pops back up. Again, it was kind of weird how it happened right after filling the tank?! Oh well... so much for the excitement! At least I learned how to read codes...lol.

 

[2003KJ]

Tim, I just went to UPS... started it up and no light. So I guess I won't be taking it in unless it pops back up. Again, it was kind of weird how it happened right after filling the tank?! Oh well... so much for the excitement! At least I learned how to read codes...lol.

Yeah that's completely normal. If it does it again, then you've probably got an issue...for now it might just be a fluke.

 

[grogiefrog]

Tim, I just went to UPS... started it up and no light. So I guess I won't be taking it in unless it pops back up. Again, it was kind of weird how it happened right after filling the tank?! Oh well... so much for the excitement! At least I learned how to read codes...lol.

Yeah that's completely normal. If it does it again, then you've probably got an issue...for now it might just be a fluke.

I left the KJ at the airport for the last several days. Early this morning when I started it up, the check engine light came back on with the same code. Look like I'll have to take it in next week. Plus I need the ball joints replaced...

Thanks Tim for your comments.

 

[2003KJ]

glad i could help...looks like the heater on your o2 sensor is shot.....that's really surprising given the age and condition of your KJ.

Do you do a lot of short distance driving with it?

 

[grogiefrog]

Do you do a lot of short distance driving with it?

It's only got under 18k on it, and yes, lots of short trips. Think that has something to do with it?

 

[2003KJ]

Do you do a lot of short distance driving with it?

It's only got under 18k on it, and yes, lots of short trips. Think that has something to do with it?

Probably. Alot of really short distance driving is hell on o2 sensors, cat. converters, and generally the exhaust system in general (plus not to mention the sludge that can build up in the engine...but I believe you run synthetic in the KJ, which helps prevent that alot)

General rule of thumb is get the engine up to temperature no matter what. And not just up to temp for like a minute or so...atleast 5 minutes. If you have to go the long way or drive around the block once or twice, do it. Better to spend the extra gas now, then have to pay for costly repairs down the line.

I've always gone by this rule and never had a single problem out of any of the o2 sensors in any of the vehicles i've owned....even the FORD!

 

[grogiefrog]

The KJ is in the shop. I dropped it off yesterday afternoon and handed the service advisor the code and what the code meant. She said, "How did you get this code?" I just told her that I knew how to get the dash to give the code, plus our forum on what it meant. LOL

I'm also having the front speakers checked under warranty as they've also had distortion at random times. I also asked about the ball joints and she told me that they have a waiting list (I'm number 15).

 

[JeepJeepster]

Hmm, thats sad. My libbys twin(or was) is in the shop.. [-(

 

[2003KJ]

LOL I can only imagine the advisor's look on her face when you handed her the code and what it meant.

Waiting list with the LBJ's.....thats pathetic.

 

[grogiefrog]

Tim, you'll be happy to know that it was the 02 sensor. Call it a win for JeepKJ.com! LOL Thanks for your help.

They didn't fix the speaker problem... and just said that they couldn't duplicate the problem. Well sure, it usually works, but I get random distortion from either of the top front speakers. I may pop them out and take a look.

As far as the ball joints, I was told that they only get two in at a time. How often is that I don't know? I'm on the list...

 

[2003KJ]

Tim, you'll be happy to know that it was the 02 sensor. Call it a win for JeepKJ.com! LOL Thanks for your help.

They didn't fix the speaker problem... and just said that they couldn't duplicate the problem. Well sure, it usually works, but I get random distortion from either of the top front speakers. I may pop them out and take a look.

As far as the ball joints, I was told that they only get two in at a time. How often is that I don't know? I'm on the list...

Glad I could help! Glad to see we could get it solved for you.