|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
Is there another way to test the
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
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
Always assemble the sensor "dry"
since the sensing surface can easily
be damaged by the solvents used in