Emissions Related DTCs

Action Taken When the DTC Sets - Type A

• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Action Taken When the DTC Sets - Type B

• The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

• The following applies to misfire DTCs:
  • If the control module detects a low level or an emission level misfire condition during 2 consecutive trips, the control module illuminates the MIL.
  • If the control module detects a high level or catalyst damaging misfire, the control module flashes the MIL at a rate of once per second.
  • If the control module detects a misfire during 2 non-consecutive trips, the stored conditions are compared with the current conditions. The control module illuminates the MIL when the following conditions occur:
    • The engine load is within 20 percent of the previous test that failed.
    • The engine speed is within 375 RPM of the previous test that failed.
    • The engine coolant temperature is in the same range of the previous test that failed.
• The following applies to fuel trim DTCs:
  • If the control module detects a fuel trim condition during 2 consecutive trips, the control module illuminates the MIL.
  • If the control module detects a fuel trim condition during 2 non-consecutive trips, the stored conditions are compared with the current conditions. The control module illuminates the MIL when the following conditions occur:
    • The engine load is within 20 percent of the previous test that failed.
    • The engine speed is within 375 RPM of the previous test that failed.
    • The engine coolant temperature is in the same range of the previous test that failed.

Conditions for Clearing the MIL/DTC - Type A or Type B

• The control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Clear the MIL and the DTC with a scan tool.