P0455

DTC P0455

SYSTEM DESCRIPTION
The DTC P0455 Evaporative Emission (EVAP) System Large Leak diagnostic detects large system leaks. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.




The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent valves.

DTC DESCRIPTOR
This diagnostic supports the following DTC. DTC P0455 Evaporative Emission (EVAP) System Large Leak diagnostic

CONDITIONS FOR RUNNING THE DTC
- Before the PCM can report DTC P0455 failed, DTC P0107, P0108, P0117, P0118, P0451, P0452, P0453, P0496, P0498, P0499, P1128, P1129, P2199, P2227, P2228, and P2229 must run and pass.
- The battery voltage is more than 10 volts.
- The fuel system is operating in closed loop.
- The fuel level is between 15-85 percent.
- The difference between the initial intake air temperature (IAT) and the initial engine coolant temperature (ETC) is between 6-10°C (11-18°F).
- The engine coolant temperature (ECT) is between 69-100°C (156-212°F).
- The vehicle speed sensor (VSS) is between 12 km/h (7 mph) and 132 km/h (82 mph).
- DTC P0455 runs once per drive cycle when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The PCM detects the EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module will turn the malfunction indicator lamp (MIL) OFF during the first consecutive trip in which the diagnostic has been run and passed.
- A current DTC, Last Test Failed, clears when the control module turns OFF the MIL.
- The history DTC will clear after the control module runs and passes 40 consecutive warm up cycles with no failure.
- Use the scan tool in order to clear the DTC.

DIAGNOSTIC AIDS
- To help locate intermittent leaks, use the J 41413-200 Evaporative Emissions System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. Introducing smoke in 15 second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
- A temporary blockage in the EVAP purge solenoid, purge pipe or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
- To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT.
- Observe the Freeze Frame/Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set . This may assist in diagnosing the condition.
- For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-3:

Steps 4-6:

Steps 7-18:

Steps 19-20:

The numbers below refer to the step numbers on the diagnostic table.
4. Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
6. This step verifies proper operation of the FTP sensor.
7. A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 inches of H2O and 7 inches of H2O.
9. This step tests the EVAP purge solenoid vacuum source between the EVAP purge solenoid and the intake manifold for restrictions or blockages.