Oxygen Sensor: Description and Operation

OXYGEN SENSOR
The engine is fitted with the plunge-proof oxygen sensor LSH 25. The oxygen sensor is potential free and is therefore fitted with a new 4-pin plug connector with separately insulated wires.

The oxygen sensor is heated by the DME control unit. Positive supply to the oxygen sensor occurs across the fuel pump relay inside the DME relay (as soon as the engine is started). The ground connection is made via the DME control unit. If the engine has already reached the operating temperature and is then driven at heavy loads and high engine speed, no additional heating of the oxygen sensor is required. In this operating state, the DME therefore cuts off the supplementary sensor heating.

The oxygen sensor is monitored by the DME control unit. The sensor voltage may additionally be read off using the System Tester and the "Actual values" menu item. If problems occur at the oxygen sensor, start troubleshooting by checking operation of the sensor heater. A voltage of approx. 12V should be present at the sensor plug when the engine is at idle.