It sets it back to the factory settings and then re-learns your driving style and adjusts accordingly. It's not instant, but allegedly worth doing. You need to drive a few hundred miles before seeing the benefits.
All you need to do is disconnect the battery and leave it overnight. Re-connect in the morning and away you go.
If I've missed anything, search the forum for similar threads. It's a popular topic.
Or ask Tom
basically it resets your car back to how it came out of the factory - so it will mean that your car will re learn all of the settings - like petrol consumption for your driving etc etc.
the main reason why most people reset their ECU is to increase their MPG - at first (after resetting it) you may experience poor MPG but after say 200 miles or about a full tank somethhing like that, the car will have learned how it needs to be driven etc and your mpg (if poor at the moment) should increase.
many 1.4 drivers have had good results from doing this, but it depends really what you are wanting to achieve from doing it
i reset the ecu (1.4) after having an industion kit and cat back exhaust fitted from which i noticed a decrease in mpg. after the reset the car was hell to drive especially when cold for a few days but everythings hunky dory know and mpg is better than its ever been. its work is all i'll say
Was just wondering but i may try that.....what is acceptable MPG on a 1.6 Brava??? i get about 300 to 320 miles from a full tank (£33 worth).....is that acceptable or do you think its worth me resetting the ECU???
OK..i will leave the ECU alone!!!.....Wasnt sure if 300 for the tank was good but having read this then it seems ok....the only reason i was worried is because i used to get about 400-450 miles out my saxo vtr...and i used to thrape that little beast!!!
Since my gearbox, decat and angeltuning, I'm pretty happy with mine. Still works out at around the 42mpg mark though around town (that's about 2 better than I used to get), and pretty much about the same on the motorway, maybe a little less due to the high revs, thanks to my lovely gearbox