Electrical gremlins or real car problems?
April 22, 2015 11:10 AM   Subscribe

My car (2012 BMW 328i xDrive Wagon E91 LCI) has two quirks: 1) battery warning after turning off the car, even after extended drives (never BEFORE starting the car) 2) brake wear warning after car has been parked in the cold for several hours (disappears after warming car up)

The car has a year left on the warranty. I've done a DIY trailer-wiring (US 4-pin) installation. I haven't taken it to the dealer yet because I'm worried the DIY job, which involved multiple wiring loom splices, will void the warranty. Trailer lights work fine.

The battery warning appears with engine off and electrical on, AFTER driving. Even extended drives, like my regular 100km once weekly trip to the ski resort. I have never seen a warning BEFORE driving, and I have never had a problem starting the car.

The brake wear warning appears after the car has been parked for extended periods in conditions below ~10C/50F. The warning consistently disappears after some driving, and does not reappear if the car was not parked for too long in the cold or was parked for extended periods in a warmer environment (above ~10C/50F).

Should I worry about any of this? Should I get it serviced? I am just concerned that the BMW dealer will require that I replace the entire electrical system and not cover it under warranty.

Note that, despite the 2012 model year, it is the previous generation 3-series (E91, not the F31). The E9x-series wagon was produced until mid-2012, unlike the sedan which transitioned to the F3x series in late 2011.
posted by wutangclan to Travel & Transportation (3 answers total)
 
Won't the dealer at least tell you what the problem is under warranty? They can't force you to make an out-of-warranty repair, can they?

Look at it this way: if it's nothing but gremlins (I know that feeling; my car tells me that it needs a service permanently; it gets reset with every six monthly service, but the warning comes back on ten minutes later) then they can tell you that. If, on the other hand, it's a real problem, you're far, far better off knowing than not.
posted by gmb at 11:59 AM on April 22, 2015


I think the battery warning with electrical on, is how it is supposed to be. These cars leave the lights on a while after stopping, if you had the lights on. Some cars run with lights on all the time. You may have an interior light on that your car warns you about. If you have your phone plugged in and charging, your car will communicate about that by the electrical warning light..

The light on after cold start, might be steering fluid low, or even coolant / antifreeze low, until warmup. I have had a cranky steering pump for a long time. In cold weather the battery and oil warning are on always for a few moments at start, this is sub-freezing temps.
posted by Oyéah at 12:16 PM on April 22, 2015


I think the battery warning with electrical on, is how it is supposed to be. These cars leave the lights on a while after stopping, if you had the lights on. Some cars run with lights on all the time. You may have an interior light on that your car warns you about. If you have your phone plugged in and charging, your car will communicate about that by the electrical warning light..

Only if you leave the car running on battery for a *long* time. (I have an older E90 BMW and I've only seen the battery warning light once in the 7 years I've had the car.)

If you're worried about the trailer wiring having voided the warranty, you could always take the car to an independent shop. They should be able to read the diagnostic codes from the car's computer and at least give you an idea as to what the car thinks is going on.
posted by asterix at 2:59 PM on April 22, 2015


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