How do you reset the ECU on a 1.6 8v vauxhall astra automatic?

To reset the ECU on a 1.6 8v Vauxhall Astra automatic, disconnect the negative battery terminal and leave it off for about 15-30 minutes. This allows the ECU to clear its memory. After the time has elapsed, reconnect the negative battery terminal and start the vehicle to allow the ECU to recalibrate. It's advisable to ensure that all electrical systems are turned off before disconnecting the battery to prevent any potential issues.