Red — stop now
Battery charge
The alternator is not charging the battery — the car runs on whatever is left in it. That is usually enough for half an hour or an hour.
A red lamp means you should not keep driving. Pull over, switch the engine off and sort it out there.
What to do now
- Switch off everything you can: heated seats, stereo, air conditioning. Headlights only if you need them.
- Drive straight to a workshop or home and do not switch the engine off without need: the next start may not happen.
- The most common cause is a broken or thrown alternator belt. You can see it with the bonnet open.
Codes usually behind it
The lamp only says that something is wrong. The code says what exactly — read it with an adapter and look it up here.
P0562System voltage lowP0563System voltage highP0620Generator control circuit — malfunctionP0621Generator lamp — circuit malfunction
What to read next
- Charging and vehicle voltage: P0560, P0620
- Alternator or battery: telling them apart
- How to check them with the app
A lamp is not a diagnosis. The same symbol lights up for a dozen different reasons, and only the code stored in the car tells them apart.
How it feels behind the wheel
The same fault shows itself in different ways. Each sign below says what to look at in the live data.
It stalls while drivingThe engine dies while the car is moving — at speed, in a corner or when lifting off. The steering and brakes go heavy at once.The voltage jumps, the lights dimThe headlights and the dashboard change brightness while driving, sometimes the battery lamp flickers. The electronics behave oddly.It cranks but will not startThe starter turns the engine over briskly, but it does not catch. Sometimes it catches and dies.It stalls at idleAt the lights, or when you lift off, the engine dies. It usually restarts straight away.
How the app helps
CarScan reads the codes behind the lamp through an OBD-II adapter, explains them in plain words and puts them into a report you can show to a mechanic.