A fault code reader is a specialist tool which is used to help diagnose sensor and electrical problems in a vehicle.

Fault code readers are usually designed for specific makes of vehicle. So for example a Ford fault code reader won't work with a Peugeot vehicle. There are some fault code readers however which have an assortment of fittings to work with a variety of manufacturers.

To use a fault code reader the tool is plugged into the vehicles code reader socket. It then receives fault codes from the vehicles ECU (Electronic Control Unit) - which is a bit like the vehicles brain - telling if there are any faults or issues the mechanic should be aware of.