2005 Jeep Wrangler TJ O2 Sensor Fault Codes P0031, P0037, P0051, P0057: Causes, Diagnosis & PCM Repair Guide

See if you can't find the electrical diagram( bbbind.com or google) to id heater circuit fuses/relays. A few voltage checks should give you some direction. Sensor internal heaters can be ohm checked.

with all 4 codes relating to both banks on different circuits......I would be checking wiring harnesses or a possible bad pcm.

wanted to add they all share same ground location for heater circuits.g105.....but also shared with other components that would cause driveability problems.do you have any driveability problems?

Not that I can tell. Just a slightly lower MPG, but that's to be expected from a bad O2 sensor.

the pcm is telling you that there is a problem with the 02 circuits.it monitors the signal and heater control for a problem.it does not know where in the circuit the problem is.the chance of bad 4 -02 sensors at same time is zero percent.you need a scan tool to see what the 02s are doing to monitor signal bias voltage to see if the 02 heaters are functional. it has to be harness/pcm connector or faulty pcm.

I know this is an old post, but did this ever get resolved? I have the exact same problem, same vehicle too. I get all four codes as confirmed codes, plus an additional code pending for 0057. I checked the heater resistance on all four O2 sensors and they read about the same. I checked the connections and thought Bank 2 Sensor 2 was lose. I reset the codes and they did not come back for a while (a few days). I'm now wondering since the 0057, Bank 2 Sensor 2, comes up twice, and when I clear codes it will come up alone sometimes, could a bad O2 Bank 2 Sensor 2 then cause the PCM to shut down the heater circuits for the rest of the sensors causing all of them to generate fault codes? I'm thinking I should try replacing Bank 2 Sensor 2? Is it a bad idea to just replace the downstream sensor, or do the upstream too. Or, should I replace all four if I have one failing? Hope that makes sense.

TJ-05 this is digging up the dead - BUT I like jeeps. here we go - P0031-O2 SENSOR 1/1 HEATER CIRCUIT LOW P0037-O2 SENSOR 1/2 HEATER CIRCUIT LOW P0051-O2 SENSOR 2/1 HEATER CIRCUIT LOW P0057-O2 SENSOR 2/2 HEATER CIRCUIT LOW Was the resistance - this is where aftermarket sensors fail. >>> It is HIGHLY recommended ONLY jeep or NTK o2 sesnors are used. These heaters are supplied from PCM and use grnd #105 So with key off probe a brown wire then key on - is there 12v? GTG

The sensors heaters all read about 4-6 ohms, if I remember. I am planing on checking the grounds and wiring, but I highly doubt it is that. These are original sensors, and the Jeep has less than 50K original miles on it. It has been a garage queen. No rust or corrosion anywhere. The engine compartment looks brand new. When CEL comes on and I pull the codes, it is all four codes coming up at once. I cleared the codes and the car ran for a week with no problems. Then they came back. That's when I thought I found a loose connection on the Bank 2 Sensor 2 one. I again cleared the codes, and they did not come back for maybe two weeks. I can see the voltages from the sensors using BlueDriver app, which is an OBI reader with limited capabilities. They fluctuate from near zero to up to nearly a volt as the PCM controls the fuel system. So, it seems it is all working fine, until well, it just through the codes again. Car runs well. I do think it seems like the CLE came on when the engine was lugging a bit going up a hill, before it downshifted, both times. Weird. Discover more OBD OBD Codes Fuse I was kind of thinking it's something with the PCM. Looking on the forums, it seems this problem comes up a lot. It seems people commonly first replace all the sensors, and when that does not work, they replace the PCM. One thread I read said his problems were caused by the two pre-cats failing, but he also had problems with the engine running properly. His pre-cats started coming apart inside and also blocked up the main cat. I don't believe I have that issue. The engine runs perfectly and the car has pretty low miles to be having problems with the cats. One person replace a relay and said that fixed his issue. I will go back and look at the wiring, checking the grounds, and to make sure the 12V is not low at the sensors or something. But it seems unlikely, since it works well until it does not. I'm not sure where to start if the wiring, grounds, and voltages check out. I guess I could through four sensors at it, that's sure a lot cheaper than a PCM, and they are old in age, even though they have only around 50K miles on them. But it seems crazy that all four are having a fault at the same time, so it seems unlikely to fix my problem. To add insult to injury, my wife's 2013 BMW 128i, just had a catastrophic engine failure with only 65K mile on it. Just out of warranty. Boy, this new year is not going so well! At least the Jeep is easy and cheap to work on. I don't like these new cars today. Cheers, Tim

Jeeps often require the ground to be cleaned #105 IS A main ground I would expect other issues if it were a bad ground. 2005 was a problematic year for jeep TJ PCMs - look at a replacement now - see If I am right. The voltage reading on scanner is SIGNAL I do not think it shows heater side. Yes the Ohm are right @4.5 spec.. AND would not have all 4 code. If one was high.

Thanks, I'm going to try to have a look this weekend. I'll check and clean up the ground. I'll check and clean the connections at the PCM too. I knew the scanner was looking at the signal lines. It dose show the PCM is managing the fuel system. I'm not sure what the fault codes are actually saying. Heater control circuit low, I think is the current is below 300ma? I could pick one sensor and put my Fluke amp meter in series with the heater circuit. I did not really want to cut and splice wires, but if I did it to the sensor wire, I could just replace the sensor at some point. If I did this I could monitor the heater current. I'm not sure if the heater current is controlled or just gets a constant current from the PCM. Maybe as the sensor heats up it's resistance changes and it is self regulating the current? At some point maybe I'll look at it from cold to hot and see exactly what happens to the heater current. Drove the car about 60 miles over the last two days and no faults. I have a lot going on right now, so I'm not sure how much I can look at it. At least I'll check the grounds at 105, and maybe also look at the ground for the PCM to make sure it low resistance too. I can check the 12V to the sensors. All that I can do pretty quick. Maybe I'll buy a PCM just to have a spare. Any advice on where or whom to buy one from? Thanks, Tim

do not cut any wires. You know what a fluke is SO this is not all over your head. Yes the PCM does moniitor heater voltage and draw - if you replace a O2 sensor you should erase the stored* heater info the PCM saves as the new one will confuse it (put simply) Only use jeep sensors, an o2 sensor can be NTK jeeps supplier G105 is a biggie for TJ electronics *disconnect battery cable will do. Let me know if anything else - its a jeep thing

Will add if I get a lead on a GOOD PCM reman.

Any updates on this? Recently purchased '05 TJ SE and its throwing the same codes. Extremely surprised no definitive answer has been found as it has been found for 14 years.

The update is this, for my case anyway. As the summer heated up, I found I was getting the four codes more frequently. If I cleared them, they would come back, usually after I drove a bit and the engine was hot. Most of the time I'd drive to town, about 15 miles, then shut off the car while I stopped for an errand. When I restarted the Jeep, the faults would come back. At that point I could no longer clear the codes, until the Jeep sat for some time and cooled off. I noticed these Jeeps get pretty warm in the engine bay. The little PCM is cooked in there. Just put your hand on it or anything around it, ouch. So, it seemed like I had a bad electrical connection, and it seems worse when the car is very hot. I had checked everything in the O2 sensor circuit several times, sensors, wiring, and grounds. I did not replace anything, because it all worked most of the time. I can monitor the signals from the O2 sensors. Everything works fine until you get these codes, which basically means the O2 heater circuit is open. Since you get all four codes, you can assume it's not the O2 sensors. It's very unlikely all four failed at once. As soon as you get the codes, the PCM stops using the O2 sensors, so the signals disappear. I'm watching the signals with a OBD2 device that has an app for my phone. Judging from what I've read, it seems the PCM on the 05 and 06 model years have issues, duh. This is reported to be one such issue, and there is also one that involves the transmission shifting badly if you have the automatic. I do, but have not had that issue as of yet. I bit the bullet, I bought off eBay a re-manufactured PCM and installed it last weekend. I've driven it quite a bit since. Some of the time it was very hot, and I was in stop and go traffic. So far, no more faults. It's looking like it is fixed. I feel there was likely a bad solder connection in the original PCM. Likely in the circuit that drives the O2 heaters. I would have put it on my bench and had a good look. However, these PCMs have about a half inch of potting covering the circuit board. I think it's some kind of polyurethane. It's about as sticky as the stuff they put in those mouse traps where the mouse get stuck in. It even looks about the same. Due to this, I decided not to mess with the old PCM. After I'm confident the re-manufactured PCM is working, I may send the original out for repair. Having a spare seems like a very good idea, still I'm not sure it could be fixed. If I had know about these PCM problems, I likely would not have bought my Jeep. When I called the dealer looking for a PCM, they told me best to check eBay for one, and good luck. You can't buy a new PCM as they are obsolete. I'm not sure how these are being "re-manufactured". Like I said, it's fully potted. You have to wonder how anyone, or any company, could remove the potting and replace any components on the circuit board. Also, this is not an easy board to replace the surface mounted components on, even if you can remove the potting. Further, how likely are they going to be able to test and repair these PCMs? For example, mine has an intermittent problem that seems temperature related. At times, I could drive for many miles without it showing up. It's likely my old PCM would bench test OK. This means if I had returned it for a core credit, they would likely resell the problem. Scary, is it not? If you can't get a PCM, the Jeep becomes a big paper weight. It's like the lithium crystals on the Enterprise. To make matter worse, you can find post going way back, where it took three, four, or even five PCM replacements to fix a problem. I'm talking post that were back when the dealer still had stock, and they were replacing them under warranty. WTF! The more you look, the more you find PCM problems. Other Chrysler and Doge products seem to come up with similar issues, when I was searching the internet. One can only hope the percentage of Jeeps having this problem looks worse than it really is, but who knows? Think about cars being built today. I think our BMW has something like twelve computers in it. Can you imagine as these cars age how difficult it will be to get these parts? The trend is the same across other makes. It's a little more than disturbing. I have a Jeep with 45,000 miles, that is in better condition than when it left the showroom floor. It may become "obsolete" over a small electronic part. This stinks, as I really like the Jeep. I wish you luck fixing yours.

Thank you so much for the update! I'm just starting my process and have ordered a PCM from Flagship 1.