Operation Manual

Oxygen Sensor Tests
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Image 8: Oxygen Sensor Tests
Oxygen sensors provide feedback to the vehicle’s computer estimating the air to fuel
ratio so that fueling changes can be made to achieve peak engine performance and clean
emissions. Therefore, oxygen sensors are arguably the most important sensors on modern
fuel-injected vehicles.
Most OBD-II vehicles perform tests on the oxygen sensors at least once per driving
cycle. The results of these tests are stored in memory for the remainder of the driving
cycle. ProScan allows you to view the results of these tests by using the Oxygen Sensor
Test tool (Image 8). Before attempting to view test results, be sure to start the engine and
allow adequate time for the tests to take place.
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