EV battery temperature warning: too hot, or a cooling fault?

What the warning actually means

The symbol is a battery with a thermometer. When the pack runs hot, the battery management system limits power and throttles charging to protect the cells. A similar lamp, battery temperature fault, means the heating or cooling itself is not working, and that one does not clear on its own.

How the cooling protects the pack

The pack has its own thermal management: a pump, a fan and sensors. While the pack is hot, the cells come first, so power is limited and charging is throttled until the temperature has come down again.

Common causes

• Rapid charging, especially several sessions in a row
• Hard driving
• A fault in the pack's thermal management: the pump, the fan or a sensor

What to do now

1. Let the car cool before charging again.
2. On the next rapid charge, precondition on the way and charge from low to around 80 percent.
3. If the light does not clear once the pack has cooled, have it read.
4. Do not open, top up or bleed the battery cooling circuit yourself.

What people often get wrong

That slow charging and this light mean the battery is worn out. Often it is the cooling that has quit, and the battery itself is fine.

When the car must go to a workshop

If it is the temperature fault lamp, or charging stays slow after the pack has cooled, have it read. Expect charging to slow or stop until it is fixed, and leave the high voltage cooling circuit to a qualified shop.

Read next

• The turtle symbol on an EV: reduced power, not a fault
• EV charging fault: usually the charger, not the car
• Traction battery fault on an EV: drive to a workshop, not a trip
• EV fast charging: why it slows down, and what actually wears
• EV range in cold weather: why it drops, and what helps

This page is general information and does not replace a professional assessment. Symbols, codes and behaviour vary between makes. Always check the handbook for your own car.