if your car is less than 10 years old and a 'check engine lamp' comes on in the instrument cluster
If you then take it to a garage and they hook it up to the diagnostic tester to read the 'Diagnostic Trouble Codes' (DTCs)they will charge you between 40 and 80 quid for this service. Instead, look into getting a 'scan tool' that will do the same job, it's almost always cheaper to buy one than pay someone else to do it, some of them are universal and should work on most modern cars, and you can use it again and again over the lifespan of that car. What you have to do is locate the special diagnostic port on your car (A 'J1962' connector that is a trapezoidal shape with 16 metal terminals in it, two rows of 8) into which you need to plug the 'scan tool'. The user guide should tell you, if not then look on the internet. Most are located in the drivers' footwell, some are hidden behind plastic panels, under ashtrays, centre console armrests etc.

Key words to look out for - 'OBD2 compliant' (On Board Diagnostics), 'J1962', 'ISO14229' and 'ELM327'. Bear in mind some are standalone interfaces with a display, others interface to your computer but laptops thesedays don't tend to have 9-pin D-type serial ports so a USB to serial interface may be required in addition.
( Rotating Wobbly Hat That's not a banana. THIS is a banana., Fri 10 Dec 2010, 1:20, 1 reply, 14 years ago)

when I saw all the text
i thought, 'here we go'
but actually a very good idea, I found one for 35 quid.
(bunglist, Fri 10 Dec 2010, 7:59, Reply)