DTC Troubleshooting: P0455, P0456 (3.5L Engine): Notes

DTC P0455 : Evaporative Emission (EVAP) System Very Large Leak Detected DTC P0456 : Evaporative Emission (EVAP) System Very Small Leak Detected

Special Tools Required

Vacuum Pump/Gauge, 0-30 inHg Snap-on YA4000B or equivalent, commercially available

Vacuum/Pressure Gauge, 0-4 inHg 07JAZ-001000B

How to use this service information .

NOTICE:

Before you troubleshoot, review the How to Troubleshoot - Refer to: How to Troubleshoot the Fuel and Emissions Systems (3.5L Engine) or How to Troubleshoot the Fuel and Emissions Systems (3.0L Engine) .
The fuel system is designed to allow the 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.

NOTE:

Fresh fuel has a higher volatility that will create greater pressure/vacuum. The best condition for testing is less than a full tank of fresh fuel. 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.