O2 sensor replacement

There are two. One is an upstream (see attached picture) and the other is the downstream which is near the catalytic converter. Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

I was getting poor milage so I had the front o2 sensor changed. The milage was great for a few months. It was around 29 mpg hw. Now it's down to the low 20's again. What can be done to bring it back to 28-29 mpg.

Has the check engine light come on? Have you double checked your work to the O2 sensor?

Thanks for answering my question. No engine light on. I had the sensor done at a local shop. I can see the o2 sensor under the car after the catalytic converter. Where's the other one located? Is it under the hood somewhere and what should I look for that can cause this problem?
Thanks again

It is an upstream sensor. It will be before the one you see in the exhaust.

Visually checked sensor wires and everything looks ok. What next ?

The only thing you can do is remove it and check it for resistance.

hello, i have a 2004 pontiac grand prix. the check engine light is on because of the bank 1 oxygen sensor. so i replaced it and reset the light. well the light came back on and so i tested it again and the message said that the oxygen sensor is defective. so i took the part back and got it replaced. i reset the light again and it came back on, with the same message. i talked to a mechanic and he told me that i have to drive the car so it can register. its been 3 weeks and the light is still on. can u help me??

Hello,

What is the Code you are getting. Your vehicle if it is dual exhaust has at least 4 O2 Sensors. If single it has at least 3. In most cases if it is a sensor it would read something like this...

Bank 1 Sensor 1 below threshold.

or Bank 1 Sensor 2

or Bank 2 Sensor 1 etc.

Usually if it just has Bank 1 lean or below threshold, could be an Exhaust Leak Vacuum Leak Fuel Pressure problems plus other causes.

.

I am getting code P0141 from my car which is apparently the Oxygen Sensor (from what I read on the net). From what I read it looks like it is Bank 1, Sensor 2...I think this means that it is the O2 sensor after/behind the catalytic convertor....can anyone confirm this?

My husband does not seem to think we should replace this as it is costly and the car runs pretty good (except on the highway, where it "surges" and hesitates intermittently). I disagree because we have a small child and I do not want to risk being stranded alongside the highway or doing further damage to the vehicle. Does anyone know how "important" it is to fix the O2 sensor?

Before I go ahead and replace this part is there anything else we should check (i.e. fuse...I would have no idea which fuse it is)

THANK YOU for any help you can give :)

Well..for the atmosphere and your wallet, it's pretty important. As far as performance and driveabililty for the car, it is not necessarily needed. It certainly won't cause your car to break down on the side of the road. It will simply cause you to have poor fuel mileage (worse than normal anyway) and some emissions will escape the car to the atmosphere that is harmful to the ozone. Oh and that annoying "check engine" light will stay on ;) If you don't have the money at the moment then you can just wait until better days, not a major concern.

i am trying to change out the o2 sensor downstream and cannot get the old sensor undone. how do i fix this? Which way do i turn it to get it to un do?

It turns counter clockwise to be removed. Before you replace the new one, place some anti seeze on the threads so you don't have this problem in the future.

How do I find and replace the oxygen sensor in my 97 grand prix

Most newer cars (1996 and above) have more than one, usually two (upstream and downstream).

They are in exhaust system. Upstream is in header or close to header, downstream is in exhaust after convertor.

Later model cars have up to four O2 sensors.

Where is(are) the oxygen sensor(s) located? Is it(they) hard to replace?

should be past the exaust manifold on the pipe going toward the catyalitic converter, either before or after the converter.

you have 1 oxy sensor and is located at the rear of the engine in the middle. its right in the center of the exhaust manifold or the very front of the pipe to the manifold.