Service Engine Soon

[skkinner]

Hello,

I have a '92 Buick Century 3.3L V6 with 129.000 km.

My problem is:

Service Engine Soon light will pop-up when engine is idling for about 2 minute after operating tempeture is riched. If I turn off and on the engine the light will shut off.
During driving the light doesn't pop-up. Anyway driving is very smooth and nice.
Idling is a little bit rough. This is an old problem but not too big.

In diagnostic mode ECM returned 44 error code.
How could I be sure that O2 sensor is defective and it needs to be replaced?

I'm afraid not to be a problem with my rough idle because the light will turn on only during idling.

Thank you very much.

[Flatrater]

I believe that a code 44 is a lean exhaust problem. Combin that with a rough runinng engine would mean a vaccum leak. Inspect your rubber vaccum leaks looking for a cracked or fallen off lines. If your car has over 50K on the O2 sensor it wouldn't hurt to replace the O2 sensor. The senors over time and heat cycles do react slower.

[skkinner]

Thank you.

Right now I've received an error code 13. So I'm pretty sure the O2 sensor is faulty.

I purchased my car with 128,000 km and I think nobody had changed O2 sensor.

[RABarrett]

Code 13 is the result of the O2 sensor voltage never rising above .4 volts or thereabouts. This code is intended to typically condemn the sensor, but do not jump to conclusions. Low fuel pressure, vacuum leaks, etc will cause the same code. Ray

[skkinner]

Hello,

I replaced my O2 sensor and everything is OK.
I think I have got a better fuel economy now.

Thank you for your help.