Catalytic Converter Replacement - keywords 4.8 5.3 6.0 6.2 P0420 P0430 converter low L59 L76 L92 LC9 LH6 LMG LM7 LQ4 LQ9 LR4 LY2 LY5 LY6 MIL P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 P0351

This PI was superseded to update model years. Please discard PIP3119E.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

DTC P0420 or P0430 found on low mileage vehicles, or DTC P0420 or P0430 set quickly after a catalytic converter was replaced.

Catalytic converter efficiency codes are disabled for the first hour of run time on all 04-07 V-8 4.8 5.3 6.0 and 6.2 engines. The catalyst efficiency codes are disabled for the first hour of run time to permit the "break-in" of the catalytic converter. There are two scenarios that may occur and induce DTC P0420 or P0430 to set.

1. If the P0420/P0430 is found on a new/low mileage vehicle use the Tech 2 to verify if there has been more then one hour of engine run time. Engine run time can be found on the Engine Hour Meter which is located in the IPC Data Display/Data 1 list. If the battery had been disconnected, or there was some other power interruption during the vehicle build process, the catalyst efficiency diagnostics may run without the one hour wait time. If the engine has not run at least one hour the Catalytic Converter may not have completed a good "break-in" cycle. This may induce a false DTC P0420 or P0430 to set. Clear any DTC P0420 or P0430 that is set before the one hour of run time. The vehicle should be driven until the Catalytic Converter reaches operating temperature. If the diagnostics for DTC P0420 and P0430 have passed return the vehicle to customer for evaluation.
2. The dealer may replace a Catalytic Converter for DTC P0420 or P0430 due to the damage caused by a previous driveability concern or misfire. The P0420/P0430 may set shortly after the Catalytic Converter is replaced. After the first Catalytic Converter is replaced there are no run time restrictions. The one hour run timer is only in the calibration software for a new vehicle. Again the Catalytic Converter may not have completed a good "break-in" cycle. This may induce a false DTC P0420 or P0430 to set. The DTCs should be cleared, and the vehicle should be driven until the Catalytic Converter reaches operating temperature. If the diagnostics for DTC P0420 and P0430 have passed, return the vehicle to customer for evaluation.

Note:  A catalytic converter needs to reach normal operating temperature to properly break-in. Normal operating temperature is 500 to 750 degrees Celsius. (900 to 1400 degrees Fahrenheit)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.