Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 1:  The Diagnostic System Check - Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. 3:  This step verifies whether the malfunction is presently occurring.
3. 4:  This step checks whether the malfunction that caused the DTC P0134 is still present. Operating the vehicle in Check Mode enhances the diagnostic capabilities of the PCM. The HO2S 1 diagnostic can be monitored on the scan tool under the I/M System Information selection. When the HO2S test displays a YES status, indicating that the heated oxygen sensor system diagnostic is completed, check for DTC P0134 in the Last Test Failed screen of the scan tool. If there is no DTC P0134 displayed, the HO2S diagnostic has run and passed, indicating that no malfunction was present this time. The DTCs MUST be cleared in order to view the Current Status of the system diagnostics being performed. Do not forget that the I/M System Information tests only indicate that the test has run, not whether the test passed or failed. The Last Test Failed screen must be checked for related DTCs in order to determine the outcome of the diagnostic test involved.
4. 5:  In this step the DMM is used as a low current voltage source taking the place of the HO2S. This step verifies whether the PCM is able to receive and process a signal from the HO2S 1.
5. 9:  A condition that affects the fuel mixture or combustion event in the engine can impact the operation of the HO2S. This can cause an accurate signal from the HO2S to fail the diagnostic. Performing the tests listed in Diagnostic Aids will eliminate a faulty running condition and prevent the replacement of a good oxygen sensor.