Test Description

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

1. 1:  The Diagnostic System Check - Vehicle 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. 2:  This step checks whether the malfunction that caused the DTC P0031 is still present. Operating the vehicle in check mode enhances the diagnostic capabilities of the PCM. The HO2S Heater diagnostic can be monitored on the scan tool under the I/M System Information selection of System Information. When the HO2S Heater test displays a YES status, indicating that the oxygen sensor heater diagnostic is completed, check for a DTC P0031 in the Last Test Failed screen of the scan tool. If there is no DTC P0031 displayed the HO2S heater 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 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. For additional information on check mode operation, refer to POWERTRAIN CONTROL MODULE (PCM) DESCRIPTION .