Gone are the days where cars were 70-80% mechanical - when DIY mechanical repairs were reasonably straight forward, if you're mechanically minded that is.
Modern day vehicles now have several on-board computers and electrical components that can make fault diagnosis a little tricky, especially without a qualified technician and/or bespoke equipment.
Modern vehicles are just as mechanical as before but now have just as many electrical components also. Newer vehicles have several ECUs (engine control units), a small handful of these are for example:
- Engine management
- Auto gearbox
- Manual gearbox
- Central control
- Air bag
and so on. In some cases the failure or absence of one control unit can cause the failure of other systems.
If you have a warning fault light illuminate on your dash it is imperative that you have it diagnosed as soon as possible at your local specialist, using your vehicle's manufacturer's diagnostic equipment to enable an accurate, quick and cost effective solution.
To save money many DIY mechanics will spend money on the basic code readers, which are easily accessible from well known sites like EBay, to diagnose a fault on their vehicle themselves. However, these readers are often basic and a multi-make system thus not giving a clear diagnosis. Many readers have a literal translation from a European language (e.g. French) to English because many of the vehicle's components are manufactured in Europe. This can in turn make interpreting the results very hard to understand, even for the professionals.
An example of a common misconception using the basic code readers is that many coil packs on the Peugeot and Citroen ‘TU' engines [1.1, 1.4 & 1.6] were replaced unnecessarily as the actual fault lied with the fuel injectors.
COMMON DIY MISTAKES
Something as ‘simple' as replacing a bulb is often carried out incorrectly. If headlamp bulbs are fitted incorrectly (upside down) there are many repercussions. Firstly it's an MOT failure, secondly the headlamp aim will be incorrect thus blinding other road users and thirdly it may burn out the light unit. Another common fault with renewing bulbs is when replacing the two pin bulbs in the rear (i.e. brake lights and sidelights) the pins can easily be bent causing interaction with other lights. For example, when applying the brakes the indicators can illuminate as well as the brake lights.
Another common mistake DIY mechanics can make is replacing a fuse that's of a higher amp rating than the original fuse fitted, which can cause the wiring to burn out resulting in a more costly repair - if you are ever unsure of what fuses are needed for your vehicle consult your local garage.