Computer problem
1995 BMW 525 6 cyl Two Wheel Drive Manual 122000 miles
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Just picked up this vehicle from a reputable used car lot.
5 miles into the drive home CHECK ENGINE light comes on. Otherwise running well and driving well
Checked all levels - fine
Also, the odometer starts to freak out and then resettles to it's 121,939 or something.
Does odometer flickers indicate set back?
What sensors trip check engine?

At that mileage I would start with replacement of the oxygen sensor. If you have access to someone with scanning equipment, the fault that commanded the check engine lamp on is in there, read it out and report back, if needed.