Vauxhall fault code reading.

Basically you bridge 2 wires and the ECU light flashes a code as to the problem.

There are 2 type of plugs, a 16 pin OBD2 which is meant to be on all cars after 1998 and a 10 pin ALDL plug which is GM specific and on most vauxhauls up to 1997.
There are also two types of fault codes, 4digit OBD2 codes for all cars after 98 with OBD2 sockets and 2 digit ALDL codes which should be given out by ALDL plug vauxhauls.
This isn't always the case though so ul have to work out which plug and codes your given yourself.

OBD2 96-99 (not meant to work after 99 soz)
To read the codes on cars with 16 pin OBD2 diagnostic plugs you bridge pins numbered 5 and 6 (see pics) with a bit of wire (paperclip, buttie bag tag).





Then turn your ignition on to position 2 where all the electrics such as electric windows and radio work, don't start the car though.
The ECU light should flash a sequence.
Each code gets repeated three times.
Those with 16 pin OBD2 plugs should give out 4 digit codes (it may give the old ALDL codes though on pre-97 cars).
Example, 10 flashes, 4 flashes, 10 flashes, 10 flashes, long pause, 10 flashes, 4 flashes, 10 flashes, 10 flashes, long pause, 10 flashes, 4 flashes, 10 flashes, 10 flashes, even longer pause would be code 0400 (10 flashes = 0) which is the code for EGR valve.

List of codes can be found here

ALDL plugs need to have pins A and B bridged

Then turn your ignition on to position 2 where all the electrics such as electric windows and radio work, don't start the car though.
The ECU light should flash a sequence.
Each code gets repeated three times.
The first code on ALDL cars is 12
So your fault code list will start and end with 1 flash, 2 flashes, pause, 1 flash, 2 flashes, pause, 1 flash, 2 flashes, even longer pause.

A list of codes is available here Click Me

Hopefully this helps.
Sorry if you've got a latter than 99 car or the fault light only flashed on/off and didn't stay on long enough to store the code.


[Edited on 29-02-2012 by Ste]