Typical Oxygen Sensor View - Actron CP9087 Service Manual

Section 2
Testing Sensors
Typical Oxygen Sensor
What is It?
The oxygen sensor is a zirconium dioxide ceramic
mounted in the tip of a threaded metal housing.
The tip is perforated to protect the sensing element
but still allow exhaust gases to pass through.
The sensor produces a voltage signal based on the
amount of oxygen it contacts. A low voltage
indicates a lean exhaust (too much oxygen). A
higher voltage signals a rich exhaust (not enough
oxygen).
The sensor must be very hot to operate: 349(C
(660(F). Many have 2-wire heating elements built-
in to quicken the warm-up time.
How it is
The computer uses this sensor to calculate
optimum air/fuel mixture for low emissions and
used?
good fuel economy. If the sensor indicates a rich
exhaust (not enough oxygen because of too much
fuel), the computer will compensate by reducing
fuel delivery. If the computer receives a lean signal
(too much oxygen because of too little fuel), it will
increase fuel delivery. NOTE: Some vehicles use
more than one oxygen sensor.
Location
The sensor is threaded into the exhaust manifold to
2-18
give it direct contact with the exhaust gases.