there you go matty
The LED will flash out a code (or series of codes if there is more than one fault) More recent ECU's have two LED's (red = first digit, green = second digit, eg red 2x flash, green 1x flash = code 21) The ECU's on most R32's have one LED, long flash = first digit, short flash = second digit, eg long, long, short = code 21.
Codes:
11 Crankshaft position sensor
12 MAF sensor circuit
13 Coolent temperature circuit
14 Vehicle speed sensor circuit
21 Ignition circuit
31 ECU (ouch!)
34 Knock sensor
43 Throttle position circuit
45 Injector leak
51 Ignition circuit
54 Auto signal to ECU
55 All OK
http://www.overflow.250x.com/
came from there
cheers
meggala