Originally Posted by MarkN

I think you have to start the engine with the fault code reader plugged in, but off. Then switch the fault code reader on and wait for the LED to flash once. Then you need to floor the accelarator for a split second within 10 seconds of the single flash.

The reader will then spit out any fault codes in the ECU, or 11 twice to indicate all clear. Once it has finished displaying the fault codes you should hear the engine speed change and it is in diagnostic mode - that's when you can use your timing lamp.

If you don't press the accelarator quickly enough after that first single flash it won't work and will just error.

This is all off the top of my head but I'm fairly sure its correct. A fault code reader without the manual is as much good as a chocolate teapot