1. Make sure the engine is off.
2. Locate the ECU. The ECU is located on the passenger side of the engine compartment, behind the battery and mounted to the firewall. It has a black plastic casing with a silver "VW" logo.
3. Disconnect the battery. To disconnect the battery, use a 10mm socket to loosen the negative battery terminal (the black one) and remove it from the battery.
4. Wait 10 minutes. This will allow the ECU to completely power down.
5. Reconnect the battery. Reattach the negative battery terminal to the battery and tighten it with a 10mm socket.
6. Start the engine. The ECU will now be reset.
Additional notes
This procedure will reset the ECU to its default settings. This may cause the engine to run differently for a short time as the ECU re-learns its fuel and ignition settings.
If the ECU reset does not resolve the issue you are experiencing, you may need to have the ECU diagnosed by a qualified mechanic.
