Mechanics

CHECK ENGINE LIGHT AT IDLE AFTER LONG TRIPS

1991 BMW M5

Computer problem
1991 BMW M5 6 cyl Two Wheel Drive Manual 181000 miles

Hello. After I drive my car for a long trip (80+ miles), the check engine light will come on with a code of 1221 (oxygen sensor) when the car is at idle, such as at a stop light. Once I start moving again, the check engine light goes away. I have a new water temp sensor, oxygen sensor, MAF and vacuum hoses. Why is this happening only at idle after long trips? Does not happen in city driving.
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Piancu
May 14, 2010.



Was the Oxygen sensor a Bosch direct replacement?

Dr. Hagerty
May 15, 2010.
No, it was a Denso oxygen sensor. It has 10k miles on it.

Tiny
Piancu
May 17, 2010.
There might be an issue with the Denso part. The system was built for a Bosch sensor.

Dr. Hagerty
May 18, 2010.