* A grounded wiring harness
* Damage
锟斤拷If a condition is found, replace the HO2S 2.
5. If no physical condition is detected and the HO2S 2 is as active as the HO2S 1 after operating the engine at 1,500 RPM for 1 min and then
returning to a stabilized idle, then replace the catalytic converter.
Repair Instructions
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 hour may correct the condition.
* Exhaust Manifold Replacement - Left Side (See: Engine, Cooling and Exhaust/Exhaust System/Exhaust Manifold/Service and
Repair/Exhaust Manifold Replacement - Left Side)
* Exhaust Manifold Replacement - Right Side (See: Engine, Cooling and Exhaust/Exhaust System/Exhaust Manifold/Service and
Repair/Exhaust Manifold Replacement - Right Side)
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (1500 Series) (See: Powertrain Management/Computers and Control
Systems/Oxygen Sensor/Service and Repair)Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (2500 Series) (See: Powertrain
Management/Computers and Control Systems/Oxygen Sensor/Service and Repair)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (1500 Series) (See: Powertrain Management/Computers and Control
Systems/Oxygen Sensor/Service and Repair)Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (2500 Series) (See: Powertrain
Management/Computers and Control Systems/Oxygen Sensor/Service and Repair)
* Exhaust Leakage (See: Engine, Cooling and Exhaust/Exhaust System/Testing and Inspection/Exhaust Leakage)
* Restricted Exhaust (See: Engine, Cooling and Exhaust/Exhaust System/Testing and Inspection/Restricted Exhaust)
Repair 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.
P0430
DTC P0420 or P0430
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0420
- Catalyst System Low Efficiency Bank 1
DTC P0430
- Catalyst System Low Efficiency Bank 2
Circuit/System Description
