ECU Reset and Error codes
Turn OFF the ignition

Connect Error code Connectors and Test Mode Connectors :
2 black connectors under dash, connect black to black and 2 green connectors under dash, connect green to green, they are by your left knee when sat in the drivers seat and often taped back to the loom if they haven't been used before.

Turn ON ignition but don't start the engine

Engine Check lamp comes on

Press accelerator pedal to the floor

Then return it to the half-throttle position and hold it there for two seconds

Release foot off the pedal completely

Start the engine

Check engine light error code is indicated by Pulsing lamp

If an error is detected then Check the ECU Code

If no error is detected - drive the car sensible for a couple of minutes
i.e. until warm (do not use boost or high rpm!)

When the ECU has been reset the Check Engine Light will flash

An Error Code is indicated by a flashing check engine light
of varying length of flash,
a flash of around once a second is the okay code and indicates all is well.

If an error code is detected Check the ECU Code

Turn ignition OFF and Disconnect Connectors

If there is a fault Check the Appropriate Sensor

Error Codes
An Error code is defined as a slow flash followed by fast flash
i.e 2 slow and 3 fast = 23 Mass Airflow sensor.
A continuous on/off at the same speed is no fault found.

Code Fault
11 Crankshaft position sensor

12 Starter switch

13 Camshaft position sensor

21 Engine coolant temperature sensor

22 Knock sensor

23 Mass air flow sensor

24 Idle air control solenoid

31 Throttle position sensor

32 Oxygen sensor

33 Vehicle speed sensor 2

35 Purge control solenoid valve

42 Idle switch

44 Waste gate control solenoid valve

45 Pressure sensor / Pressure exchange solenoid valve

51 Neutral position switch

Worth noting the above is age dependant. Newage cars have a different process to the classics.

Ah, Ok bud I will stand corrected!