E10 Checking the Oxygen (Lambda) Sensor

E10 Checking the oxygen (Lambda) sensor





The oxygen (Lambda) sensor provides one of several input signals that are processed by the control module to determine the correct fuel-air mixture. Other input signals include engine rpm, engine temperature, accelerator position and air mass.

The oxygen (Lambda) sensor used in the LH system incorporates an electric preheating function which enables the temperature to be raised quickly so that accurate monitoring of the composition of the exhaust gases is ensured.

1 Unplug the two-pin connector from the wiring harness.

2 Use the multimeter to measure the resistance across the two white connections of the oxygen (Lambda) sensor. The correct resistance is about 4 ohms.

3 Connect the multimeter (2-V DC scale) prods to the black lead of the oxygen (Lambda) sensor and ground.

Start the engine.

As the temperature of the sensor rises, it starts to emit a signal of between 100 and 900 mV. The actual signal will vary with the fuel-air mixture, so that a lean mixture of the kind caused by a slight vacuum leak will give a Lambda value >1 and a signal voltage of about 100 mV.

A rich mixture will give a Lambda value >1 and a signal voltage of about 900 mV.