Quick answer
A diagnostic should involve reading fault codes, checking live data, inspecting likely causes and explaining what needs testing or repairing next.
Common symptoms and causes vary by vehicle, but the safest next step is to get the fault checked before continuing to drive if the car is in limp mode, smoking heavily, overheating, losing power badly or showing repeated warning messages.
- Send the registration and a photo of the warning light if possible.
- Explain when the issue happens and whether the car drives normally.
- Do not rely on clearing fault codes without finding the cause.
- Book diagnostics if the warning returns or the car feels different.
