DTC P1456: EVAP Control System Leakage (Fuel Tank System)

NOTE: The fuel system is designed to allow specified maximum vacuum and pressure conditions. Do not deviate from the vacuum and pressure tests as indicated in these procedures. Excessive pressure/vacuum would damage the EVAP components or cause eventual fuel tank failure.

Special Tools Required

Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX

Please note that this is a two-trip code, once cleared, it cannot be reproduced in one trip. Also, certain specific driving and ambient conditions must occur before the ECM/PCM will complete the system checks. Additional test drives may still not meet the specific conditions needed to reproduce the code.

Therefore, follow these troubleshooting procedures carefully to ensure the integrity of the system and to confirm the cause of the problem or code.

NOTE: Fresh fuel has a higher volatility that will create greater pressure/vacuum. The optimum condition for testing is fresh fuel, and must be less than a full tank of gas. If possible, to assist in leak detection, add 1 gallon of fresh fuel to the tank (as long as it will not fill the tank), just before starting these procedures.