Recently had a fault code of 21 which denotes as a coolant sensor.
I have just spent nearly 2 hrs changing this as it is located in the most awkward place especially if you have big hands. Mmmmm
Anyway as I said. I have just changed this and have followed instructions for an ECU reset.
Plug in test wires and fault wires, Turn on ignition - NO Faults
Press down on throttle all the way then half for 2 seconds.
Released then Started car.
Took it for a nice little drive with no boost.
Check engine light started flashing after a couple of mins to let me know that the ECU Has reset.
Pulled over, Turned Engine off and just left fault wires in place,
Turned on ignition and there it is FLASH.......................FLASH..FLASH.
21 again?????????
don't understand?
Does an ECU Reset wipe out memory of previous faults or is it telling me that I still have a fault.
Check engine light, NOT lighting up under normal conditions.
Can anyone throw any light on this please.
Cheers
Matt

 

BTW Car in question is a 95 UK Turbo

 

try dissconecting the battery for an hour. that will reset ecu. i own a 93 wrx.

stew

 

cheers stew, Will try tomorrow