Catalytic Converter Break-In Information To Prevent DTCs P0420 And/Or P0430 - keywords 4.8 5.3 6.0 6.2 break low L59 L76 L92 L9H LC9 LFA LH6 LH8 LMF LMG LM7 LQ4 LQ9 LR4 LY2 LY5 LY6 P0300 P0301

This PI was superseded to update model years and Recommendation/Instructions. Please discard PIP3119F.

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

A SES light may be experienced on low mileage vehicles, or vehicles that have recently had the catalytic converter replaced. Upon inspection, DTCs P0420 and/or P0430 may be stored.

On a new vehicle, catalytic converter efficiency DTCs P0420 and P0430 are disabled for the first hour of engine run time to allow "break-in" of the catalytic converter. The following scenarios may allow a DTC P0420 or P0430 to set after this hour of engine run time has expired:

1. If these DTCs are found on a new/low mileage vehicle, use the Tech 2 to verify engine run time on the Engine Hour Meter in the IPC Data Display/Data 1 List. If the engine run time is less than one hour, the battery may have been disconnected, or another vehicle power loss event may have occurred, during vehicle manufacturing. This may allow the catalyst efficiency diagnostics to run before one hour of engine run time has been achieved. If this occurs, the catalytic converter may not have completed a thorough "break-in" cycle, causing a false DTC P0420 and/or P0430 to set. If this occurs, clear the DTCs and perform the drive cycle below.
2. If the DTCs set shortly after the catalytic converter is replaced, it may be a result of the engine run time restrictions no longer being in place since the vehicle is no longer new. As a result, the catalytic converter may not have completed a thorough "break-in" cycle after replacement, possibly resulting in a false DTC P0420 and/or P0430. If this occurs, clear the DTCs and perform the drive cycle below.

In order to achieve proper catalytic converter temperature and allow the mat material to out-gas (break-in), perform the following drive cycle and suggestions:

1. drive vehicle at sustained highway speed for 25 to 30 minutes
2. bring vehicle to a stop
3. shut off the engine for 1 minute
4. restart the engine and resume highway speed for an additional 10 to 15 minutes
5. bring vehicle to a stop
6. shut off engine for 1 minute
7. restart the engine and operate vehicle at the conditions for running the DTC P0420/430 tests and assure that the vehicle passes these diagnostic tests. If the diagnostics for DTC P0420 and P0430 have passed, return the vehicle to customer for evaluation. If the diagnostics do not pass, perform SI diagnostics and repair as necessary.

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.