Battery — charging system failure
The red battery icon warns that the charging system is not working: the alternator delivers no current or less than required. The car is running on battery energy — you have tens of minutes.
What this indicator means
The indicator is tied to the voltage differential between the battery and the alternator output. With a healthy alternator the terminal voltage is 13.8–14.5 V with the engine running; if voltage drops to battery level (12–12.5 V) or below, the lamp fires. The cause can be mechanical (broken belt) or electronic (voltage regulator failure).
Common causes
- Broken or slipping alternator drive belt
- Failed voltage regulator
- Worn alternator brushes
- Oxidised or loose battery terminals
- Burnt-out rectifier diode bridge inside the alternator
- Discharged or failed battery (no longer holds charge)
What to do as a driver
Immediately switch off all non-essential consumers (A/C, heaters, audio) — this extends the runtime. Get to a safe location or workshop. Keep a voltmeter in the glovebox: if terminal voltage while running is below 13 V, the alternator is not charging.
Safety
Critical: 20–60 minutes until full discharge. Avoid night driving without lights. Do not shut off the engine — you may not restart.
Related DTC codes
- P0562
- P0620
- P0625