If the engine management ECU detects a fault, in addition to storing the code for interrogative diagnosis, it will also flash the Check Engine light a number of times to indicate the broad nature of the fault.
Turn the ignition on, wait for the Check Engine light to go out, and then count the number of subsequent flashes. If there is more than one code, there will be a pause of 2 seconds between flash sequences
Trionic:
2 Flashes - MAP sensor
3 flashes - Intake air temperature sensor
4 flashes - Coolant temperature sensor
5 flashes - Throttle position sensor
6 flashes - Oxygen sensor (lambda probe)
7 flashes - Fuel / air mixture
8 flashes - EVAP valve
9 flashes - faulty ecu
LH/DI
2 flashes - ROM check (check sum check)
3 flashes - Watchdog (control module fault). This fault can also be caused by a defective spark plug or defective ignition discharge module.
4 flashes - Knock sensor (no signal or signal incorrect)
5 flashes - Engine load signal from LH or pressure from the manifold absolute pressure (MAP) sensor incorrect.