DTCs P0420 and P0430 are Type A DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0420 and P0430 are Type A DTCs.
Reference Information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Electrical Information Reference
Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic Trouble Code (DTC) List - Vehicle)
Circuit/System Verification
1. Verify that no other DTCs are set.
锟斤拷If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle).
2. Operate the vehicle within the Conditions for Running the DTC while observing the scan tool Catalyst monitor Not At Idle Test Conditions
Met parameter. The parameter will change to Yes when the OFF Idle Conditions have been met.
锟斤拷If not the specified value, operate the vehicle within the OFF Idle Conditions.
3. When the parameter has changed to Yes and the conditions are safe, stop and idle the vehicle in gear.
4. Apply the service brake.
5. Monitor the scan tool Catalyst Monitor Test State parameter. When the parameter indicates Active, the Catalyst Monitor Test is running.
6. Continue to monitor the parameter. When the parameter indicates Inactive, the Catalyst Monitor Test has completed.
7. When the test has completed, the Catalyst Monitor Test Counter Bank 1 or Bank 2 parameter will increment by one and the Catalyst Monitor
Test Result Bank 1 or Bank 2 parameter will indicate Pass, Fail, or No Decision.
锟斤拷If no decision has been made, repeat steps 2-6 until the Test Result parameter indicates a Pass or Fail.
Circuit/System Testing
Caution: Refer to Heated Oxygen Sensor Resistance Learn Reset Caution (See: Powertrain Management/Computers and Control
Systems/Oxygen Sensor/Service Precautions/Heated Oxygen Sensor Resistance Learn Reset Caution).
Note: A new converter with less than 161 km (100 mi) on it may set DTC P0420 or P0430 due to out-gassing of the internal matting.
Operating the vehicle at highway speeds for approximately 1 h may correct the condition.
1. Engine idling, observe the DTC information with a scan tool. Verify there are no HO2S or misfire DTCs set.
锟斤拷If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle) to diagnosis the applicable DTC before proceeding with this diagnostic procedure.
2. Verify the following conditions do not exist with the catalytic converter:
* Dents
* A severe discoloration caused by excessive temperatures
* An internal rattle caused by damaged catalyst substrate
* Restrictions-Refer to Restricted Exhaust (See: Engine, Cooling and Exhaust/Exhaust System/Testing and Inspection/Restricted Exhaust
).
锟斤拷If a condition is found, replace the catalytic converter.
3. Verify the following conditions do not exist with the exhaust system:
* Leaks-Refer to Exhaust Leakage (See: Engine, Cooling and Exhaust/Exhaust System/Testing and Inspection/Exhaust Leakage).
* Physical damage
* Loose or missing hardware
* Improperly torqued HO2S
锟斤拷If a condition is found, repair the exhaust system.
4. Verify the following conditions do not exist with the HO2S 2:
