2003 325xi wagon with just under 150,000 miles; one owner past 8 years; serviced regularly; no major mechanical problems during this time. 18 months ago the ABS, Brake, EML, ADB+T/DSC, SEL lights began to come on unpredictably and intermittently. Sometimes all of them; sometimes some of them; sometimes all at the same time; some times sequentially. Totally unpredictable. The car has continued to run well with no problems except warning lights. Since that time the BMW- factory- trained- but- not -dealership mechanics have: replaced fuel cap, replaced idle control valve, replaced intake manifold adjuster, replaced front brake pads, rotors, sensor, oil separator, hoses, replaced throttle housing, replaced caliper and discs, replaced throttle housing (under warranty), replaced throttle motor and idle control valve. AND THE LIGHTS STILL COME ON! The car continues to perform without mechanical problems during this time. Does anyone have any ideas what is going on? And, how to get the lights from coming on? Thanks.
Is there anyway you can isolate this so that you can decide whether it is a brake problem or an engine problem? Is there a way to disable the ABS temporarily? Maybe ask your mechanic.
Did anything happen just prior to noticing this? Like was any work done on the brakes? Pads replaced? If so, just a wild guess, but sometimes a pad replacement, if done incorrectly, can confuse or even damage the ABS system.
The warning lights are usually tied to the alternator field circuit for the test mode of the warning lights. I suspect that the alternator is causing the trouble with the lights.