Hi everyone. I just got my Cobalt SS the other day. Its a 2006, with 57K on the clock. The day I got it, I did light driving from where I bought it and to town. Then, yesterday morning, I started it up to move it from where it was in the driveway, and the CEL is on! So, I took it right to AutoZone and had the codes read. They came up P0054. The printout says this...

02 (oxygen sensor) heater condition - check repair resource for sensor location identification. Edplenation - the powertrain control module controls the electrical circuit for the oxygen sensor ehater. The computer has recognized a failure in this circuit.

Probable Cause -
1. Check circuit fuse
2. Relay defective
3. Check circuit wiring

I have searched in the forums, but I really couldnt find anything. I have no idea where the rear O2 sensor is located either, I havent really had time to poke under the hood. Could somebody please give me some help? Thanks.

 

Not to be mean but if you don't know where an O2 sensor is take the car back where you bought it or to another professional. Again, not meant to be disrespectful but the O2 sensors are one of the easiest parts to locate/change/ect.

If autozone is correct in the causes you don't need to find the sensor anyways. You might wanna check the issues that are listed since I'm not familiar with that exact code.

Just my .02

 

None taken. Like I have said before, I really havent had time to poke around to look for it. Isnt the second one on the DP? I have an SS 2.4 is that helps.

 

second is located AFTER cat on the DP. Since I doubt you have access to a better scan tool or a DVM, I'll make it quick down and dirty.

Remove and replace after cat o2 sensor AFTER you have checked the 12+ feed to the heater circuits (on a cobalt this is located in the underhood fuse block...I cannot remember which one it is, but the manual your car came with should label that for you. Check fuse, if good, crawl under car and unplug the suspected 02 sensor, check to make sure the harness hasnt touched the pipe or has gotten burnt. Visually check the harness connectors at both 02 sensor and harness. If it appears to be good, reconnect, recheck for the code after clearing it, if it comes back after three key on cycles, without showing any other codes to indicate you have a harness problem or PCM problem, replace sensor recheck, enjoy a CEL free drive.

 

Thank you! Im going to give this a shot right now. Ill let you know how what happens!

 

Thanks for the walk through.... So heres what I did. Checked the fuse, it was okay. I removed the positive cable for the wire. Then, went on the the next step, jacked up the car and got underneath. I removed the O2 sensor, and checked the wire the whole way up to the plug. Everything looked okay to me. So, I let it hang for a bit, screwed it back in, and tucked the wire nice and snug behind the heat sheild. Hooked up the battery, got in, and gave it about 8 key turns. The CEL finally went away when I started it up. Only thing is, when the key is on the accesory, the light is still on. Is it supposed to do this? And how long do you suppose the CEL will stay off?

 

It's the Emisin Fuse in the under hood fuse block. 10 amps.

 

Yepp, I found that out from the manual. My fuse wasnt blown though, so I really dont know what I did to make the CEL go away, but it did. I just dont know for how long. But for some reason, until I actually start my Cobalt, the light will stay on. Is this normal?

 

Because the heater element in the o2 sensor is only turned on when the vehicle is started on a cold start. When you turn the key to acc the heater isnt energized. So the ecm dosent see the fault.If you have an ohm meter you cant test the resistance of the heter element to see if its open or too high.

 

The CEL stayed off for about 250 miles, it just came back on this afternoon. Anything else I should check?