Understanding Codes

[tim]

My check engine light came on my 2009 chevy aveo, I got the 4 codes P0054, P0138, P0141, and P0140
it looks like it has something to do with the o2 sensor or the harness, has anyone had this problem, and am I better off to take to dealer to get it fixed or try to replace the o2 sensor myself?

[Daox]

All you need to replace an O2 sensor is an adjustable wrench. Its really pretty easy to do. Your codes isolate the O2 sensor behind the CAT, not the one before it. Shouldn't take more than 10 minutes to do.

If you find the old O2 sensor hard to get out, you can try penetrating oil (I never had good luck with the stuff), or use a torch to heat up the threaded area of the pipe. Once its pretty hot give it another go with the wrench. A cheater bar helps too if its being stubborn.

Good luck.

[2010AveoLT]

I ran all the codes through my scan tool, and they are all related to the Downstream Oxygen Sensor; the P0140 signifying that the Downstream O2 Sensor has Completely ceased to function. Daox's advice is 100% accurate, although I'd like to add that you can rent/buy a special Oxygen sensor socket at your local parts house very cheaply.

[avguy]

I haven't replaced O2 sensors on my Aveo yet, but just did the upstream on my Dodge Caravan earlier this week. That one was not coming off without the slotted socket - no way, no how. Don't know if the Aveo is like this, but it might be a good idea to have special O2 sockets on hand, just in case. I got a set of O2 sockets as a loan-a-tool from Autozone - $25 deposit, which was returned in full when I returned the sockets the following day. If it doesn't break free right away, instead of applying external heat, one other way is just running the engine until warmed-up. I did that with my van, which made it easy to free-up the sensor.