1991 BMW M5 Check engine light at idle after long trips

Tiny
PIANCU
  • MEMBER
  • 1991 BMW M5
  • 6 CYL
  • 2WD
  • MANUAL
  • 181,000 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.
Friday, May 14th, 2010 AT 11:53 AM

3 Replies

Tiny
DOCHAGERTY
  • MECHANIC
  • 9,603 POSTS
Was the Oxygen sensor a Bosch direct replacement?
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Saturday, May 15th, 2010 AT 9:14 PM
Tiny
PIANCU
  • MEMBER
  • 2 POSTS
No, it was a Denso oxygen sensor. It has 10k miles on it.
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Monday, May 17th, 2010 AT 6:53 PM
Tiny
DOCHAGERTY
  • MECHANIC
  • 9,603 POSTS
There might be an issue with the Denso part. The system was built for a Bosch sensor.
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Tuesday, May 18th, 2010 AT 9:37 AM

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