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Testing lambda sensor

Question : MY 1997 Citroen Xantia 2.01 has an exhaust lambda sensor that is suspected to be faulty, causing the engine to idle roughly.

My mechanic tells me that the lambda costs around RM1,200, and the only way to confirm if my unit is faulty is by swapping it with a new one.

Is there another way to test the lambda sensor?

Answer : THE lambda or oxygen sensor tells the engine control unit (ECU) if there is too much or too little fuel entering the engine in order that adjustments can be made.

The Xantia uses a four-wire sensor -- two wires supply power to the heater, and the remaining two are signal wires.

The sensor can easily be tested using a high-impedance voltmeter, such as the digital types.

First, measure the resistance between the two heater wires. It should show a resistance of no more than 12 ohms.

Next, start the engine and mea- sure the voltage at the signal wires. The voltage should vary between 0.5 and 1.0 volts.

The absence of a voltage, or if the voltage does not vary, indicates a malfunctioning sensor.

Always assemble the sensor "dry" since the sensing surface can easily be damaged by the solvents used in gasket sealants.


Irritating sensor

Where is the sensor ?

ABsolute coincidental

Erratic rpm

Oxygen sensor

Lambda always lights up

Drop sensor in boiling water

Check sensors

Testing lambda sensor

Sensing trouble


ABS-olute non-sense

Sensor fault

'Ping' hassle

Wrong readings

Barely audible

Faulty sensor

Faulty 02 sensor

02 sensor

Lambda symbol

Oxygen sensor

Spark plugs
Timing belt


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