Hey guys. My sister has an automatic 2002 525i with around 120k. Upon pulling into her parking lot last night, it went into limp mode. It is now displaying “Transmission Fail Safe Prog”. After a little digging it appears that it could be a problem with the transmission (obviously), the TPS, or the alternator/battery. I haven’t been over there to look for leaks or check the trans fluid, but I should be able to tomorrow.
What’s the next move? Is this something that should be brought right to the dealership or should I have someone clear the codes and test the alternator/battery? Any other ideas? Any help is appreciated. Thanks!
First I would obviously check trans fluid level to make sure you’re not overlooking anything obvious.
Check her voltage at idle and see what it reads. If low, it could be alt/batt. It’s probably a regular alternator, not the water cooled type, so that’s a big plus if that happens to be the problem.
Check any codes with a reader. Hop onto bimmerfest and look up the codes in their big directory (search posts by a user named bluebee). Luckily people seem to have the same problems over and over, and each topic is usually researched in great depth over there.
Don’t just check the voltage, actually take the cables off the battery and clean them up good. I was helping a neighbor with a weird electrical issue on an Altima last year and voltage tested out fine and the connections looked good. Still really seemed like a battery issue so I loosened up the terminals and where I couldn’t see they were corroded really bad. Cleaned them up and the car has been fine since. My guess is the corroded connection wasn’t an issue with the tiny draw my volt meter needed but when it came to passing the high amperage load the car needed it wasn’t good enough.