Engine Code 0155 won't go away

I keep getting this engine code (0155, O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 1) even after I spent the money to replace this O2 sensor. The code just won't go away. Is there anything else I need to replace or check?

I can reset this computer and sometimes it won't reappear for a day. Other times I reset it and it comes back within a few minutes.

One mechanic told me the Computer was shot but I have a hard time believing that as I know they are fairly reliable.

Can anyone help me?
Thanks in advance.

What year rodeo? I had the same thing over a year ago on our 2002 3.2L. Are you 100% you changed the right O2 sensor? If so, you might have a break in the wire (one of the two) to the heater coil in the sensor. The sensor will work fine w/out the heater, just wont warm up as fast, + obviously you wont get the CEL to go out without it. The 2002-2004 rodeo 3.2L are a ROYAL pita to find direct fit O2 sensors for :banghead: . I tried SEVERAL aftermarket units that said they'd fit but didnt. Wound up getting a new OEM one thru stcharlesauto.com for ~$120:crying: . Local dealer wanted ~$200:rolleyes: .

Joel

I actually have the redesigned 3.5L 2002 Rodeo but my guess is that it doesn't matter.

I actually didn't do the work myself. The local mechanic (not a dealership) near where I live did. He seemed like he knew what he was talking about. I think I was charged about $200 for everything.

Could he have not replaced the right one? Is this something I could DIY? Troubleshoot myself?

I change my own oil, cleaned the EGR, etc but never played around with the O2 sensors. I also don't have a hoist to get under there very well. I'm willing to give it a try if you think I can do it. At least I should try and take a look. What are your thoughts?

Anything I should be looking for? Maybe the wire is broken. Would this be something that I could easily troubleshoot? CEL is driving me crazy and I'm tired of resetting the comp.

I would start by making sure your mechanic changed the right one:uhoh: . Bank 2 sensor 1 is the driver's side, before catalytic converter sensor. (bank 2 sensor 2 is drivers side AFTER cat) There are 4 O2 sensors total, 2 per side. All 4 sensors are the same p/n and interchangeable on the 2002-2004 rodeo 3.2's. The OEM sensors are denso. I bought an O2 sensor socket set from oxygensensors.com and did the r/r myself. Originally I purchased a 'walker' brand replacement O2 sensor, but the plug is different. oxygensensors.com took it back and I ordered an OEM denso thru stcharlesauto.com. It's a tight, knuckle-buster job, but not too bad. It also takes a minute to figure out how to squeeze/pry/slide the electrical connectors apart:banghead: .

G/luck
Joel

I actually have the redesigned 3.5L 2002 Rodeo but my guess is that it doesn't matter..


Redesigned 3.5L? A 3.5L rodeo didn't exist in 2002 :smokin:. 2000-2004 rodeo 3.2's are pretty much the same, electronics and all.

Joel

Swap the O2 sensors around and see if the code follows.

BTW, it really hacks me off when I hear mechanics always pushing people to buy new ECM's because they don't have the brains to find out whats REALLY GOING ON!

Yeah I like to get my hands dirty so I think I will try it myself. I will try and swap the sensors around and see if the trouble code follows.

Totally agreed on the mechanics recommendation. I highly doubt this is an ECM issue. And just for mentioning the ECM, I bet there's a good chance he replaced the wrong one. Of course he will never admit that though. Should have just done it myself, I guess I got a little lazy :)

Thanks guys. I'll let you know how it goes.

Yeah I like to get my hands dirty so I think I will try it myself. I will try and swap the sensors around and see if the trouble code follows.

Totally agreed on the mechanics recommendation. I highly doubt this is an ECM issue. And just for mentioning the ECM, I bet there's a good chance he replaced the wrong one. Of course he will never admit that though. Should have just done it myself, I guess I got a little lazy :)

Thanks guys. I'll let you know how it goes.I don't see how he could deny replacing the wrong sensor, especially if you crawl under your Rodeo and see that Bank2 Sensor1 is old and dirty and Bank1 Sensor1 (for example) is brandy new. :2cents:

Looks like he replaced the right sensor because that's the only one that's still looks new.

Going to swap them and see if the problem follows. The sensor definetely works fine once the car is warmed up. I can reset the code and it doesn't come back while driving.

Looks like he replaced the right sensor because that's the only one that's still looks new.

Going to swap them and see if the problem follows. The sensor definetely works fine once the car is warmed up. I can reset the code and it doesn't come back while driving.


Well, O2 sensors don't work at all until they reach about 700 degrees F. This is normal.

This is the final update on this problem.

Changed O2 sensors and guess what? The error now showed up in the back. I imediately drove to the shop that performed the work and told them my findings. They are ordering a new O2 sensor and installing it free of charge (damn right they better, even though I enjoyed getting my hands dirty).

The mechanic never came out and admited his fault but he mentioned that when someone mentions Bank 2 sensor 1 to him he thinks passenger side (HA HA HA HA). Not in the Isuzu it isn't.

Thanks guys for all the kick ass information here. Maybe I can go for more than a month without seeing the CEL once this O2 sensor is replaced.

I love my Rodeo when it's running good but the past few months have been a little trying. Needed new Intake Manifold Gaskets (warranty) and now the O2 sensor and the ABS issue seems to be rearing it's ugly head every once in a while. Other than that this vehicle has been great and I tow a boat in the summer without any problems. Since using seafoam before oil changes also, you can barely hear the engine running and it never burns any oil. Using 10w-30 year round.

Thanks again!

Cool you were able to track it down with the help here! ECM, eh?

As stated earlier, cylinders 1,3,and 5, from front to back, are on the passenger side and are Bank 1. That leaves 2, 4, and 6 on the driver's side for Bank 2.