Dashboard warning lights on a used car · what to check

What it usually means

• Engine management light with no drivability change · often a sensor, EGR or emissions-related fault.
• Limp mode · usually boost, fuelling or gearbox protection, and rarely cheap.
• Light that has been cleared just before viewing · codes reappear after a drive cycle, so drive it.
• Airbag or ABS light · an instant test failure in most markets.

How to check it on the forecourt

1. 01Turn the ignition on and confirm every warning lamp lights, then goes out · missing bulbs hide faults.
2. 02Plug in a cheap OBD reader and read stored and pending codes, not just live ones.
3. 03Drive for at least 15 minutes including a motorway pull, then re-read.
4. 04Ask for the invoice on any recent 'light fixed' work.