I had to reset the ecu today, when it was replaced with the new one. This is how i was told to do it: put the key in the ignition, turn it to the setting where all the lights are on the dash. Pump the accelerator *5* times (all the way to the floor) then turn the ignition off. Wait 30 secs. Then turn on. It doesnt seem to do much really, it just erases any errors collected by your on board computer when you stall your car etc. I guess it has to re-learn your driving style, so give it a dose of optimax and a good thrashing after youve done it and i guess itl do something? (im no mechanic or anything, just doing what i was told to do by one!)