What Are Car Diagnostics?

diagnosticsSo what exactly does the term “Car Diagnostics” mean? Suzanne Keane explains all

One of the most common complaints you hear about garages these days is how much they charge for “switching off” a dash light or for “plugging the car into the computer”.  But what is it they actually do?

Since the early 90s most cars have come equipped with an E.C.U. (Engine Control Unit). Over time these have grown – and become more complicated!

Car diagnostic software is built into all modern cars and helps to keep your vehicle running smoothly. Basically what it does is read the E.C.U. constantly and reports back with any issues – which are how airbag lights and engine check lights can appear. The software also keeps a record of everything going on in the car.

In simple terms, by plugging a device into the port on your car you can see faults which have appeared and may be causing problems. This tells the mechanic what needs to be done to get everything back in working order.

But it’s not always as easy as checking the code in a book!  The real problem can hide behind a combination of different fault codes and that’s where training and experience makes a difference. Also, diagnostic machines are expensive to buy and unfortunately that means the cost will be passed on to the customer.

However, there is a way of avoiding diagnostic charges…..  buy a vintage car!


Suzanne Keane

12th October, 2015


Author: Suzanne Keane

A confirmed petrol head with a penchant for Retro VW’s, Suzanne has been taking apart (and sometimes putting back together) her own cars for years! You can follow Suzanne on Twitter at @_suzannekeane

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