What is a car diagnostic check?

If your car has developed a fault or have warning lights come up on your dashboard, then a garage may recommend that you have a diagnostic run on your vehicle. This can range in price from £30 upwards to £100 depending on where you take it.

So what exactly is a car diagnostic check and how can it help with a fault? All modern vehicles have an on-board computer inside them which is linked up by sensors to different components within your car. These computers monitor things such as engine temperature, oxygen levels and replay issues and any faults found are stored on the on-board computer in a series of fault codes.  These fault codes need to be read by specialist equipment called a diagnostic machine. Not all garages have this equipment and even if they do, not all garages have the right software to read your make and model of vehicle.

When put on the machine, the on-board computer will display a list of fault codes which can indicate to the mechanic where the fault may lie. It may pop up faults that are not currently causing an issue and often just a rest is enough to clear an intermittent fault.