I have a 2000 Chevy Blazer 4.3 2 door 2wd Automatic. My question is:

My service engine light came on, I had the codes checked at Autozone, here is what it said.

TROUBLESHOOTING P0141
Determined a malfunction exist in O2 sensor 2 in bank 1. O2 sensor 1 is closet to the cylinder head. While 2 or 3 are downstream typically past the catalytic converter or in it.

Where exactly can I find O2 sensor 2 in bank 1. Is in mounted in the pipes or what, also, is there any thing I should be cautious of when installing? Thanks for any help you can give me. I have already bought the Bosch replacement for it.

Start at the catalytic converter. Follow the pipe going towards the front of the vehicle. The first 02 sensor you come to will be the one you're looking for. It'll be easier than changing the easiest spark plug on my '97...look under the car right at the passenger door...there it is sticking straight out of the exhaust pipe pre-cat converter.

I have a 2000 Chevy Blazer 4.3 2 door 2wd Automatic. My question is:

My service engine light came on, I had the codes checked at Autozone, here is what it said.

TROUBLESHOOTING P0141
Determined a malfunction exist in O2 sensor 2 in bank 1. O2 sensor 1 is closet to the cylinder head. While 2 or 3 are downstream typically past the catalytic converter or in it.

Where exactly can I find O2 sensor 2 in bank 1. Is in mounted in the pipes or what, also, is there any thing I should be cautious of when installing? Thanks for any help you can give me. I have already bought the Bosch replacement for it.


A code does not say replace the sensor.
Code 141 is a 02 sensor heater or wiring circuit problem.
Check all wiring and also fuse.
Always check it out first.

Link removed by me because of moderator concern on copyright material.

Thanks a ton for the help. I checked all the wires the mechanic I talked with said it would be in my sensor since they were all good. Can this account for my pitiful gas mileage as well?:eek:

Thanks a ton for the help. I checked all the wires the mechanic I talked with said it would be in my sensor since they were all good. Can this account for my pitiful gas mileage as well?:eek:

It is more of a 02 sensor heater problem.
May help a little on mileage.
Has the mileage dropped down a lot or has it always been bad?

Its happended recently, I was getting 18 or so now its about 14. I am changing my pcv valve as well. I put in the sensor, not bad at all, now I have to wait on the computer to reset to check it out. Thanks again to all of you!!

Also, what about the EGR, I have 65000 k on it. Does it need changing?

Its happended recently, I was getting 18 or so now its about 14. I am changing my pcv valve as well. I put in the sensor, not bad at all, now I have to wait on the computer to reset to check it out. Thanks again to all of you!!

Also, what about the EGR, I have 65000 k on it. Does it need changing?

As long as EGR valve is working with no EGR valve codes it should be OK.
You are welcome and let us know how it goes or if gas mileage does not come back.

Thanks a ton for the help. I checked all the wires the mechanic I talked with said it would be in my sensor since they were all good. Can this account for my pitiful gas mileage as well?:eek:

Bank 1 sensor 2 is after the catalyst and will not affect fuel mileage at all. That sensor monitors catalyst performance only.

Bank 1 sensor 2 is after the catalyst and will not affect fuel mileage at all. That sensor monitors catalyst performance only.

O.K. Thanks, I replaced it as Chris said, and reset the light, it has not come back on so I guess its Ok. Will the PCV effect mileage?

A fault in the PCV system could affect fuel mileage adversely. It could also set a number of DTC's.

If mileage dropped suddenly and no codes is the temp running at 195 cause at cold the PCM will be running the system rich and 98up one temp sensor for gage and PCM. Then clean the MAF in the air intake especially if using an oiled K&N filter.

Thanks a lot, I will do that today.

Went ahead and replaced all O2 sensors, made a pretty big difference in gas mileage, from 14 gpm to 17.5

How many miles are on the vehicle?

Almost 70k