P0455

Schematic:

Once every drive cycle, the EVAP system runs a 25-40 second diagnostic where it monitors possible leaks, the fuel tank pressure sensor, bent value, and the canister purge value. This diagnostic has 5 phases and can set several different codes depending on which part of the diagnostic fails. The evaporative emission system is tested by applying pressure (vacuum) to the system and monitoring pressure decay. The ECM monitors the vacuum level through the fuel tank vapor pressure sensor. In the fourth phase of the diagnostic, the EVAP vent solenoid is commanded closed (normally open valve) and the EVAP canister purge valve is commanded to a fixed duty cycle, allowing the engine to draw a vacuum on the entire evaporative emission system. After a calibrated vacuum level is achieved, the EVAP canister purge valve is turned off, sealing the system. If a sufficient vacuum pressure level cannot be achieved, a large leak fault is detected.

DTC PARAMETERS
DTC P0455 will set when:
^ Vehicle speed = 0 mph
^ Engine speed = Idle
^ Fuel system is in closed loop
^ Engine Temperature at start is between -8.25°C (17°F) and 75°C (167°F)
^ IAT is between -8.25°C (17°F) and 50.25°C (122°F)
^ Battery voltage greater than 11.05
^ Engine runtime greater than 1 min. 45 sec.
^ Altitude less than 9000 ft.
^ Fuel Level between 1.85 and 14 gal.
^ No TP, ECT, VSS, fuel tank pressure, oxygen sensors, idle control purge valve, vent valve, battery voltage, misfire, or EGR code set.

DTC P0455 is a (type B) DTC.

DIAGNOSTIC AIDS
The following could result in a large leak:
^ Missing, improperly installed (loose) or faulty fuel cap.
^ Disconnected or damaged EVAP vent hose.
^ Disconnected, damaged, pinched or blocked fuel tank vapor lines.
^ Damaged or leaking EVAP canister.
^ Leaking fuel sender assembly or O-ring.
^ Leaking fuel tank or filler neck.
^ Stuck open EVAP purge solenoid.