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.

This step determines if the fault is present. The vehicle must be at operating temperature.

This step checks whether the malfunction that caused the DTC P0134 is still present. After performing the scan tool clear DTC information function, the DTC P0134 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If DTC P0134 appears in the Not Ran Since Code Cleared list, the P0134 diagnostic has not yet run. When DTC P0134 does not appear in the Not Ran Since Code Cleared list, the P0134 diagnostic has run. If the MIL is NOT illuminated and there is no Pending DTC Status in DTC Information, the P0134 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. The Not Ran Since Code Cleared list only indicates whether of not the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.

This step checks for a voltage on the HO2S signal circuit. When the oxygen sensor is disconnected the scan tool should display 80 mV or less.

This step checks for an open in the HO2S 1 ground circuit.

This step checks the HO2S 1 signal circuit. The DMM is used as a low Current voltage source, taking the place of the HO2S. This test verifies whether the signal wire is good, and whether the PCM is able to receive and process a signal from the HO2S.

A possible cause of a voltage short to the HO2S signal circuit is water. Check the wiring harness and PCM connectors for water that may cause ignition positive voltage to be shorted to the signal circuit.

Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0134 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0134 appears in the Not Ran Since Code Cleared list, the DTC P0134 diagnostic has not yet run. When the DTC P0134 does not appear in the Not Ran Since Code Cleared list, the DTC P0134 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0134 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.