oxygen sensor

1. Which one?
2. What has prompted you to change an O2 sensor?

i think they said bank1,and its because my check engine light came on

Are you sure you are not just shooting the messenger instead of attacking the problem?? The sensor is supposed to give error messages when things are out of kilter. What is the exact code that was stored? If the sensor is accusing something in the system of being out of range, the first thing you do is consider what may cause that and address that problem. O2 sensors these days are expensive enough to almost cove a diagnostic fee to be sure you are repairing/replacing the correct parts.

Lugnut

i dont know what the code was i brought the truck to a garage and they said it was the oxygen sensor.what else could it be

There are many things that can result in an out of range O2 sensor reading. A qualified techwith a good scanner can check other calues in the system that may indicate a problem other than the sensor. As I said, the sensor is just the messenger in most cases. Many less than qualified techs get a bad reading on a sensor and immediately replace the sensor just to find out the sensor was telling the truth. That is why the exact code and an understanding of what may cause that code to be set is important. You may need to ask the a few questions to learn why they condemned the sensor. The sensor may be the problem - I just want to point out that several other things can result in a bad sensor reading.

Lugnut

I wonder how many good O2 sensors have been replaced because of a vacuum leak.

Enough to retire both of us very nicely

Lugnut

Not only that but on top of the original problem there is often at least one other problem created by junk parts or improper installation making diagnosis even more difficult. Bob

Hear Hear!!!. Nothing like "experienced parts" when troubleshooting. replacing parts that cannot be proven defective is a good way to end up chasing your tail. Even replacing those you CAN prove defective is sometimes troublesome. I have a 1994 Trans Sport 3.8 which I bought with a toasted engine 4 years ago. I put a new rebuilt engine in, with a new Bosch O2 Sensor. On the first long trip (to Florida from Ontario) the engine misfired occaisionally and eventually turned on the check engine light and threw a code (can't remember the number) indicating it was running lean. I figured it was a bad O2 sensor, but was unable to prove it 100%, so I put in a new one (under warranty). That summer I attempted to tow my 17 foot trailer, and could not go

30km without having it act up. I checked EVERYTHING - neglecting te now twice replaced O2 sensor. I finally gave up and sold the trailer after not using it for 2 summers. Then last winter it started doing the stutter/cut out thing again - and putting the CEL on while driving to work. I put the OBD tester on, with it monitoring O2 sensor voltages and when it started acting up, I found the voltage stuck at 0.44 volts. That is neither rich, nor lean - and the code (when it finally showed)said engine lean.The sensor was going open circuit, and we were reading the ECU supplied bias. I put in a new AC Delco O2 sensor and have not had the problem in the last 11 months. This is not an isolated incident. There are an AWFULL lot of defective, dead in the box, parts being sold today - and if you install one while troubleshooting it WILL ruin your day!!!.