Common causes
A weakening high-voltage battery, a blocked hybrid battery cooling fan or filter, an inverter coolant fault, or a 12-volt battery problem.
The 12-volt battery
Hybrids still have a small 12-volt battery. When it is weak it can cause odd warnings and a no-start, and it is a cheap first check.
Safety
High-voltage components are dangerous. Do not open the hybrid battery or orange cables yourself.
What to tell the mechanic
Make, model and year, the warning message, kilometres, and whether the petrol engine runs more than usual.
Safe to drive?
If the car drives normally, book in soon. If it loses power, will not go into ready mode or shows a red triangle with limp mode, stop and arrange a mobile check or tow.
General guidance only, not a diagnosis. If in doubt, do not drive it and have it inspected. In an emergency, call 111.
Who can help
Get quotes for hybrid & ev mechanic near you
Questions
Does the hybrid battery always need replacing?
No. Cooling faults and individual module problems can sometimes be repaired. Get a proper test first.
What should I put in the job?
The warning message and any codes.