02 sensor can affect.... ?

[pooskay]

My check engine light popped up the other day....90k miles ... seems like the common reason for the check engine light coming on is due to a bad 02 sensor. But can this cause a loss in power? My acceleration is not what it used to be. Thanks for the feedback.

[El Presidente]

the o2 sensor shouldnt cause a noticiable drop in power, but im not sure. Loss of power is usually the result of engine compression loss or a dead cylinder.

[the///man]

02 sensor would give you poor gas mileage and an unstable idle

[Andrewsd1985]

A faulty O2 sensor can do many higns to your car and poor performance could be one thing. The O2 sensor sends bad info to the ecu and you air/fuel ratios are screwed up, very likely problem.

[EXtech]

I would have the fault codes checked. Especially with 90K on the odometer. I would suspect a clogged catalytic converter.

[EXtech]

..and by the way, I would also replace the O2 sensor as well.

[Furious]

Originally posted by pooskay@Dec 15 2003, 08:12 AM
My check engine light popped up the other day....90k miles ... seems like the common reason for the check engine light coming on is due to a bad 02 sensor. But can this cause a loss in power? My acceleration is not what it used to be. Thanks for the feedback.

it will affect power because the car is essentially running in safe mode (like a computer sort of) because the signal is bad to the DME the car runs the car in a sort of "safe mode" where the car purposely dumps more fuel into the car then normal to compensate for any possible situation that the car could run without the readings of the O2 sensor. this is why its typical to notice poor fuel mileage and somewhat poor performance .

[bigred318]

if your o2 sensor isnt working, then your car is going to make sure it wont hurt it that much anymore, hense the lack in powerm get it fixed and im sure it will be right back, maybe even a little stronger.
David

[pooskay]

great feedback, thanks for all the replies...i will post an update soon.

[pooskay]

btw, my fuel mileage has also dropped down, so it could very well be the 02 sensor.

[EXtech]

Have you noticed any rotten smell from the car/exhaust, like a rotten egg or sulfur smell?

[pooskay]

no, but its giving off a very heavy fuel smell when i start it up....a couple times when i started my car (cold start), the engine shook/vibrated for about 5 seconds and struggled to reach a stable rpm..seemed like it was going to shut down, but never did.... but that only happened twice out of many starts.

[EXtech]

See this is where it can get costly and difficult because while the 02 sensor is a likely cause, there are also many other possibilities that lurk. Another possibility is the crankcase vent valve or any type of vac. leak. The fuel smell could be because of either. If there is a vacuum leak or a bad maf (any type of lean condition) then the DME is going to correct this by dumping more fuel which will cause the 02 sensor to go frantic. Same possibility with a coolant temp sensor. All the added fuel will then create the fuel smell. However, a bad catalytic converter can do the same just in a slightly different fashion. I could go on and on, just too hard to quickly diagnose the problems that you're having without fault codes.

[pooskay]

well i took it to my mechanic and he got an "undefined" code. ill probably take it to a bmw shop next time....thanks again for the info!

[EXtech]

undefined meaning what? did it just say "undefined" or was there anything else along with it??