Electrical and sensor faults on a used car · what to check

What it usually means

• Blank or rebooting screen · head unit or software, often dealer-only.
• Multiple unrelated faults at once · earth, loom or battery health rather than four failures.
• Windows, mirrors or central locking failing on one side · door loom wear.
• Intermittent faults that clear on restart · module or connector, and hardest to prove later.

How to check it on the forecourt

1. 01Sit in the car and operate every switch, window, mirror, lock and seat motor.
2. 02Cycle the infotainment, reversing camera, Bluetooth pairing and climate controls.
3. 03Open and close each door fully while watching for flicker on the dash.
4. 04Read stored codes across modules, not just the engine.