BMW battery and charging warning
A red battery light while driving means the alternator isn't charging the battery: the car is running on the battery alone and will stop when it's empty. Turn off what you don't need and get somewhere safe.
A yellow battery message, or "increased battery discharge", means the battery is weak or was drained while parked. Newer BMWs also need a new battery registered after it's replaced, or the car keeps charging it like the old one.
Usual causes
- The alternator or its regulator.
- The drive belt, or its tensioner.
- The cables and connections between the battery, the alternator and the starter, including corroded ground straps.
- An old battery that can't hold its charge, or something draining it while the car is parked.
- A battery replaced without being registered, on cars that need it.
What to do
- Read the faults in the engine module and the power or battery modules: they record charging and voltage faults, and on newer BMWs the battery's own history.
- Check the battery's health and charge: the battery health how-to shows how.
- After a new battery, register it on cars that need it: the battery replacement how-to shows how.
General guidance from how BMWs work, not a diagnosis of your car: the fault the module stored, with its details, tells you more.
The fault codes behind it
- Engine electronics fault codes 5694 codes · E46, E52, E53, E60, E61, E63, …
- Power module fault codes 46 codes · E60, E61, E63, E64, E65, E66, …
How-tos
Reading the fault
AutoLingo for BMW reads the fault behind the light from the module that stored it, in plain English and with its details, and clears it after the repair, with BMW's own diagnostic protocols: a generic OBD2 code reader only reaches the engine's emissions faults. See what it does on your BMW.
Questions
- Can I keep driving with the red battery light on?
- Only as far as you must: the car runs on the battery alone and will stall when it's drained, losing power steering and brake assist with it.
- Why does my BMW need a new battery registered?
- Newer BMWs adjust charging to the battery's age and type. Registering a new one tells the car to start over, so it doesn't overcharge it like a worn battery.
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