I have a 05 Cobalt totally stock with 69k miles with a check engine light on... I have the codes P0171, P0133, P0131... I replaced the O2 sensor located right behind the motor, I guessed that was bank 1, hoping it was that but no..., checked the air cleaner for tightness and fit, it looks good , the mass air flow sensor looks clean but who knows? Any ideas???? I know this problem has been covered a million times so any info would be great! I really don't have a lot of time and money to take it somewhere. Thanks

 

Baro or MAF...I had the same **** a few weeks ago. Order it from CED, it's not expensive and easy to replace.

 

CED? whats that, and wheres that?

 

Crate Engine Depot, I tried finding the part on their website, but couldn't track it down...just call them (877-441-5150) and tell them you need a BARO sensor for your 2005 Cobalt SS, and they should be able to hook you up. Ships quick too.

The BARO is the sensor that sits above your oil filter plug. takes 2 min to swap out.

 

Just remember when you replace or check something and you know you fixed it, if you dont reset the check engine light (WHICH IS A BAD THING TO DO!!!) the car must go through 40 cycles of turning on the car warming up and then being shut down (so 40 times of actually driving the car somewhere). It needs to pass itself every time to turn off the CEL. Reason why it is bad to reset the cars memory of CELs is because (lecture time!!) you lose the important information your car uses and has learned from the whole time you had your car. Replacing the O2 sensor will definitely be one of those times you reset the cars computer because of the learning effect the car does from having an old O2 sensor. Try resetting the cars computer via unplug battery or get a scan tool and clear CELs. Try that and post what happens.

 

Oh well... I ended up taking it to a shop today....hopefully they can find the problem and not cost me very much.... yeah right... I'll let you know the outcome....

 

You're going to be pist when I told you it's a $50 sensor and they charge you $225 for it.

 

Well I guess I'm glad I took my Cobalt to the shop...the problem was a wrong O2 sensor was installed by the old owner causing the light to come on.( I just bought the car on 6/27/10 for my daughter) The car needed a UP STREAM O2 sensor, so I guess the guy installed a down stream O2 sensor. I had no clue, the O2 looked new when I looked at it in the car. So I guess the lesson here is to be sure you get the right parts from your parts guy. So I guess the $142.00 charge was worth it because I would still be buying and replacing parts and getiing pissed off...