Application Guide

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trademark of Robert Bosch GmbH and/or its affiliated entities.
The worldwide leader in oxygen sensor technology
Bosch invented the automotive oxygen sensor in 1976, and has
been at the forefront of the technology ever since. We work
closely with vehicle manufacturers worldwide to create the
most efficient and reliable systems to keep your vehicle running
smoothly. Our experience with vehicle manufacturers means
we have the capability to produce parts that meet vehicle
specifications.
What is an oxygen sensor?
An oxygen sensor detects the amount of oxygen in a vehicle’s
exhaust system and sends a signal to the Engine Control
Unit (ECU), which adjusts the amount of fuel delivered to the
combustion chamber.
f Too much oxygen in the exhaust or too little fuel being fed to
the engine indicates a lean mixture, which can cause
performance problems.
f Too little oxygen or too much fuel in the exhaust indicates a rich
mixture, which results in lower MPG and excess emissions.
Either condition can shorten the life of the catalytic converter,
which removes harmful pollutants from the exhaust.
Almost all gasoline powered vehicles since 1986 have at least
one oxygen sensor, and vehicles manufactured since 1996
will have at least two. There is one sensor located before the
catalytic converter to communicate with the Engine Control
Module (ECM) to let the car know if it needs to use more or less
fuel. A second sensor is located after the catalytic converter to
make sure that the catalytic converter is working properly.
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Engine Control Unit (ECU)
Receives information from the primary oxygen
sensor regarding the amount of contaminants in the
combustion system.
Mass Air Flow (MAF) Sensors
A MAF sensor measures the exact amount of air
entering the vehicle’s engine. The sensor then
transmits this information via an electrical signal to
the ECU.
Fuel Injector
Based on a signal received from the ECM, the fuel injector
delivers the right amount of fuel to the combustion chamber
— resulting in the optimal air-fuel mixture in the engine.
Spark Plug
The spark plug produces the spark that ignites
the air-fuel mixture in the combustion chamber of
gasoline engines.
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Upstream Oxygen Sensor
Positioned before the catalytic converter, these sensors
send engine air-fuel reference signals to the ECU so that
fuel delivery is adjusted to optimal working conditions.
Downstream Oxygen Sensor
The downstream oxygen sensor monitors the efficiency of
the catalytic converter and sends signals regarding how well
the vehicle’s catalytic converter is working.
Catalytic Converter
Removes contaminants from the combustion system.
Without the correct air-fuel mixture provided by the
ECM, the catalytic converter cannot eliminate harmful
pollutants from the exhaust gases.
Combustion Chamber
The fuel injector sprays fuel into the combustion chamber.
Fuel is then projected into the cylinder, removing all of the
oxygen and igniting the the spark plug.
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Bosch Oxygen Sensors