Tracking Down And Fixing DTC P1456 Problems (ASN 0803-02)

TRACKING DOWN AND FIXING DTC P1456 PROBLEMS

TECHNICAL SERVICE BULLETIN

SERVICE INFORMATION

The causes for DTC P1456 [EVAP control system leakage (fuel tank system)] can be very simple, or they can be a pain to track down and fix. If you have done all of the published tests and everything passes, yet the vehicle comes back with the same code, it might be necessary to keep the vehicle overnight. This allows the vehicle to fully cool, and may expose the elusive problem. Prepare the vehicle by clearing the DTC from the PCM memory before the overnight cool down.

In the morning, check the fuel tank pressure sensor (FTPS) voltage before starting the engine (key ON, engine OFF). If the FTPS is at or near 2.5V, do the REPAIR PROCEDURE in Service Bulletin 99-040 , Troubleshooting DTC P1456 and P1457, before starting the engine. This bulletin is for '99-00 3.2 TLs, but the repair procedure can be used for other vehicles.

If the FTPS condition shown above does not exist, or no problem was found when you checked the system using Service Bulletin 99-040 , start and drive the vehicle. If there's a leak in the system, it may only be present during the transition period as the vehicle warms up. After driving the vehicle a short time, check for temporary DTCs. If temp DTC P1456 has been set, the system has detected a leak. As indicated above, use the REPAIR PROCEDURE in Service Bulletin 99-040 , Troubleshooting DTC P1456 and P1457 to locate the leak.