How do you reset the ecu on the 206 hdi 2 liter turbo d?

To reset the ECU on a Peugeot 206 HDi 2.0 Turbo Diesel, disconnect the negative battery terminal and leave it disconnected for about 15-30 minutes. This allows any residual power to drain and can help reset the ECU. After reconnecting the battery, start the vehicle and let it idle for a few minutes to allow the ECU to recalibrate. If necessary, you can also use an OBD-II scanner to clear any error codes directly from the ECU.