P0455
DTC P0455
System Description
The Evaporative Emission (EVAP) System is used to store fuel vapors to reduce the amount of unburned fuel from escaping into the atmosphere. The EVAP system consists of the EVAP canister, the fuel tank pressure (FTP) sensor, the EVAP lines and hoses, the EVAP canister purge solenoid valve which is normally closed, the EVAP service port, the EVAP canister vent solenoid valve which is normally open, the fuel tank, and the engine control module (ECM). The ECM monitors the EVAP system for circuit faults in the FTP sensor, the EVAP canister purge solenoid valve and the EVAP canister vent solenoid valve circuits. The ECM also monitors the EVAP system for small and large leaks. During the DTC P0455 diagnostic, the ECM monitors the FTP sensor for an atmospheric pressure reading when all of the DTC parameters have been met with the engine running. The ECM will then command the EVAP canister vent solenoid valve ON which is a closed valve, and command the EVAP canister purge solenoid valve to a fixed duty cycle. The ECM will let the pressure drop in the fuel tank for a certain length of time after which it will turn OFF the EVAP canister purge solenoid valve. DTC P0455 sets when a certain vacuum in the fuel tank could not be achieved due to a large leak or a lack of vacuum source.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0455 Evaporative Emissions (EVAP) System Large Leak
Conditions for Running the DTC
* Before the ECM can report that DTC P0455 failed, DTCs P0446, P0449, P0452, P0453 and P0496 must run and pass.
* DTCs P0068, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0220, P0452, P0453, P0502, P0601, P0602, P0604, P0606, P060D, P060E, P062F, P0641, P1133, P1516, P1621, P2101, P2120, P2125, P2135, P2138, P2176 are not set.
* The system voltage is between 11-18 volts.
* The EVAP canister vent solenoid valve is commanded ON, closed.
* The EVAP canister purge solenoid valve is commanded ON, open.
* The engine is running.
* The fuel tank level is between 15-85 percent.
* The barometric pressure (BARO) is more than 74 kPa.
* The engine coolant temperature (ECT) and the intake air temperature (IAT) at engine startup are between 4-30�C (39-86�F).
* The ECT and the IAT are within 8�C (15�F) of each other at engine start-up.
* The throttle position (TP) angle is between 7-35 percent.
* The vehicle speed is less than 137 km/h (85 mph).
* The DTC P0455 diagnostic runs once per ignition cycle after the above conditions have been met.
Conditions For Setting the DTC
* If the FTP voltage is less than 3.0 volts during the DTC P0455 diagnostic test indicating a vacuum cannot be pulled on the EVAP system, DTC P0455 will set.
* The above condition exists for longer than 5 minutes and 30 seconds.
Action Taken When the DTC Sets
* The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
Conditions for Clearing the MIL/DTC
* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
* The ECM uses the FTP sensor to detect the amount of vacuum pulled on the EVAP system during the leak diagnostic tests. Ensure that the fuel pressure sensor is not skewed by verifying the FTP sensor on the scan tool is between 1.30-1.70 volts with the ignition ON and the fuel cap removed.
* If DTC P0455 fails, a warm test will be performed and can only pass, not fail, a diagnostic test. The purpose of this test is to keep the malfunction indicator lamp (MIL) OFF during the initial test if the customer starts the vehicle with the fuel cap off.
* Visually inspect for a large leak in the EVAP system. Locate the leak with the J 41413-200 (J 41413-100) Evaporative Emissions System Tester (EEST).
* The following are possible causes of a large leak:
- The fuel cap is missing, is incorrectly installed or is leaking.
- The EVAP canister vent solenoid valve is stuck open.
- The EVAP canister purge solenoid valve is stuck closed or is blocked.
- The EVAP vent hose is loose or is damaged.
- The EVAP canister is leaking.
- The fuel sender assembly O-ring is leaking.
- The fuel tank or filler neck is leaking.
- A condition may exist where a leak in the EVAP system only exists under a vacuum condition. By using the scan tool Purge/Seal function to create a vacuum, seal the system and observe the fuel tank pressure (FTP) parameter for vacuum decay, this type of leak may be detected.
Test
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