I went to Autozone and they told me that one of my O2 sensors is bad. They said it is "BANK 1, Sensor3" I noticed that there are 4 sensors... 1 in each manifold pipe and one before and 1 after the converter. Can anyone tell me which one I need to replace??????? The guys at Autozone could not tell me which one it is.

Thansk for all your help,
Mike

 

Just a note of caution. I went to Autozone on another vehicle last year. The scan tool came back and said O2 sensor Bank 1 or 2. I was casually told that the sensor needs to be replaced. I went to someone I trusted and they said to look for other symptoms. It turned out that I had a slit in my vacuum hose near the backside of the engine in my truck. I wasn't sure I could hear it and I couldn't find it using carb cleaner (a trick I was told about). The only way I finally found it was by putting my hand physically on the vacuum hose and feeling along the entire vacuum route until I discovered the slit/hole. The hose itself was not replacable but the entire vacuum harness was and only cost me about $40 bucks plus an hour of my time taking the old off and installing the replacement( Had to remove a few simple items first to gain entire access, no big deal though).

My caution is this: The sensor may actually be working, and it's telling you that there is a problem with your emission's. Possibly a fuel mix or an over abundance of oxygen (as in my case, vacuum leak). The only way to know that the sensor itself is working is of course to test it. With a volt-ohmeter or such, but to just go out and replace it may prove to be expensive and futile. But, sensors do eventually stop working right also. I'm dealing with a Service Engine Soon light myself and think I'm on the right trail still but that is another post altogether.

 

Yeah if it says something like "O2 sensor heater circuit malfunction" or "O2 sensor low input" or somethin like that, it may not actually be your O2 sensor.

I don't like to tell people that the sensor's bad when those codes come back because it's not always the sensor. I usually reccomend they have it checked out by a professional.

If you are hell bent on replacing it, Bank 1 is the drivers side of the engine, sensor 3 is the first one after the cat.