1989 BMW 535i • 6 cylinder 2WD Automatic • 220,000 miles

The check engine light goes off after the engine is rev up a few times on my 89 e34 535i it sometimes comes back while driving but a stab of the accelerator usually sorts it. Performance is down when light is on.
December 8, 2010.

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on.

Dec 8, 2010.
The engine management system used on that particular vehicle is usually quite robust. In this case, it is most likely the Oxygen sensor and it is setting the light because of its age and response time. If the Oxygen sensor does indeed require replacement, use the Bosch original equipment unit, other manufacturers sensors have slightly different calibrations that can sometimes cause trouble. At 220k miles, it is probably time to have an overall inspection performed as well.

Dr. Hagerty
Dec 8, 2010.