1991 BMW M5 Check engine light at idle after long trips

1991 BMW M5
181,000 MILES • 6 CYL • 2WD • MANUAL
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PIANCU
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  • 2 POSTS
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.
May 14, 2010 at 4:53 AM
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DOCHAGERTY
  • ✓Experienced Mechanic
  • 9,606 POSTS
Was the Oxygen sensor a Bosch direct replacement?
May 15, 2010 at 2:14 PM
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PIANCU
  • MEMBER
  • 2 POSTS
No, it was a Denso oxygen sensor. It has 10k miles on it.
May 17, 2010 at 11:53 AM
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DOCHAGERTY
  • ✓Experienced Mechanic
  • 9,606 POSTS
There might be an issue with the Denso part. The system was built for a Bosch sensor.
May 18, 2010 at 2:37 AM
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