Hybrid cars rely on both a 12-volt auxiliary battery and a high-voltage traction battery, and failure of either can cause serious disruption. A dead 12-volt battery may leave the vehicle unable to start, while a traction-battery fault can reduce performance, trigger warnings or prevent the hybrid system from restarting; prompt attention is important because the petrol engine may not operate independently.

The 12-volt battery powers the car’s computers and accessories, and can often be jump-started only through the specified terminal. Traction-battery warnings can also stem from overheating or blocked cooling vents rather than a failed pack, but drivers should follow dashboard instructions, consult the manual for towing guidance and avoid touching orange high-voltage cables or battery components.