Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

1. 1  - The Diagnostic System Check - Engine Controls prompts the technician to complete some basic checks and stores freeze frame data, if applicable. This creates an electronic copy of data taken when fault occurred. Information is then stored on scan tool for later reference.
2. 3  - This step verifies whether malfunction is a hard failure or an intermittent.
3. 4  - This step verifies whether PCM is able to receive a signal from the HO2S 1. DMM is used as a low current voltage source taking place of the HO2S.
4. 8  - A condition that affects fuel mixture or combustion event in the engine can impact operation of the HO2S. This can cause an accurate signal from HO2S to fail the diagnostic. Performing tests listed in Diagnostic Aids will eliminate a faulty running condition and prevent replacement of a good oxygen sensor.