Any benefit in replacing O2 sensors?
 

My '92 with 140K miles has the original o2 sensors. No check engine light and several years ago my mechanic said they were working fine. Even before then, the mileage seemed worse then it used to be, 16 mpg city, and the exhaust seems rich in gas. If they are bad, will there always be a concrete sign such as a warning light? If I were to change them in the above conditions, should I expect to have any noticable benefit? Thanks. Bill Z

Re: Any benefit in replacing O2 sensors?
 

I would guess no. Bad 02 sensors are not timid about causing a code. :)

Re: Any benefit in replacing O2 sensors?
 

They can get "lazy" before they actually trigger a code. After 100,000 miles they are due for replacement but not necessarily worn out. If you replaced them it would not be money wasted at 140,000 miles.

Re: Any benefit in replacing O2 sensors?
 

Thanks for the thoughts. I may give it a try when I have some time just to see what happens. Bill Z

Re: Any benefit in replacing O2 sensors?
 

My car is like that 20 MPG highway. With 114,000 on it. I put new O2's in and it has not realy made any differnce, But I think I have something else wrong. I get a check engine light some times.

Re: Any benefit in replacing O2 sensors?
 

It most certainly does make a difference. I was getting bad gas mileage in my 94 Legacy Turbo wagon, and then put in a new subaru O2 sensor and my mileage shot up almost five miles a gallon.:eek: Just make sure your car is properly tuned up to get the most benefit.

Re: Any benefit in replacing O2 sensors?
 

I had replaced both of mine at the same time (165,000) and both of them looked like they severely needed to be replaced. (throwing code 32, running rich, smelling gas).

I didn't notice an improvement in gas mileage but at least it's operating fine and not throwing codes or killing me with gas fumes. I would say replace them before they inevitably fail if your just looking to do some preventative maintenance.

Re: Any benefit in replacing O2 sensors?
 

What is a tune up?:confused: