Free tool
Fault Code Decoder
Warning light on? Enter the code your scanner shows for a plain-English explanation, the likely causes and a rough idea of the cost — before any garage gives you a number.
Codes look like P0420, P0300, C1234, U0100…
Estimates are indicative UK ranges for guidance only — actual causes and prices vary by vehicle, and a stored code points to a system, not always the exact part. That’s the whole point of a proper diagnosis: knowing the real fault before you spend. Not affiliated with any vehicle manufacturer.