Battery — amber warning
The amber battery icon appears on modern cars with Start-Stop — a warning, not a critical fault. It means the battery lacks the reserve to restart the engine after a light-off stop.
What this indicator means
The BMS (Battery Management System) measures internal resistance, capacity and voltage. When wear reaches threshold (typically 70% of original capacity), the module auto-disables Start-Stop and turns on the indicator — to preserve start capability after every stop.
Common causes
- Natural AGM/EFB battery wear (typically 3–5 years)
- Long standstill (alarm, key drain)
- Many short trips without full recharge
- Faulty BMS sensor (winding on the negative terminal)
- Alternator not fully charging
What to do as a driver
Run a battery test (free at most workshops). If capacity below 70% — replace with a matching AGM/EFB. Fitting a cheap "regular" battery instead of AGM = instant BMS error. Battery replacement requires BMS reprogramming via a service tool.
Safety
Informational/important: winter no-start risk. Fix before cold season.