P0455

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The evaporative system includes the following components:

^ Fuel tank

^ EVAP canister vent solenoid

^ Fuel tank pressure sensor

^ Fuel pipes and hoses

^ Vapor lines

^ EVAP tank pressure control solenoid vacuum valve

^ Fuel tank pressure control valve

^ Fuel cap

^ Evaporative emission canister

^ Purge lines

^ EVAP canister purge valve

The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors vacuum level via the Fuel Tank Pressure sensor signal. At an appropriate time, the EVAP canister purge valve and the EVAP canister vent solenoid are turned ON, allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or a faulty EVAP canister purge valve is indicated. A DTC P0455 can be caused by the following conditions:

^ Disconnected or faulty fuel tank pressure sensor

^ Missing or faulty fuel cap

^ Disconnected, damaged, pinched, or blocked EVAP purge line

^ Disconnected or damaged EVAP vent hose

^ Disconnected, damaged, pinched, or blocked fuel tank vapor line

^ Disconnected or faulty EVAP canister purge valve

^ Disconnected or faulty EVAP canister vent solenoid

^ Disconnected or faulty EVAP tank pressure control vacuum solenoid valve

^ Open ignition feed circuit to the EVAP vent solenoid, EVAP canister purge valve and the EVAP tank pressure control solenoid vacuum valve

^ Damaged EVAP canister

^ Leaking fuel sender assembly O-ring

^ Leaking fuel tank or fuel filler neck

^ Disconnected or damaged fuel tank pressure control valve

Conditions for Running the DTC

^ Engine coolant temperature between 70°C (158°F) and 110°C (230°F).

^ Intake air temperature between -10°C (14°F) and 50°C (122°F).

^ Barometric pressure greater than 75 kPa.

^ Calculated Mass Air Flow (MAF) greater than 5 - 30 g/sec.

^ Fuel tank level is between 25 and 75%.

Conditions for Setting the DTC

^ Fuel tank pressure change.

^ Purge accumulation time greater than 200 seconds.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after one ignition cycle in which the diagnostic runs without a fault.

^ Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for problems in any of the following components:

^ EVAP canister

^ EVAP canister purge valve

^ EVAP canister vent solenoid

^ EVAP tank pressure control solenoid vacuum valve

^ Fuel tank pressure sensor

^ Fuel tank pressure control valve

For functional checks of the components listed above, Refer to Enhanced Emission (EVAP) Control System. Evaporative Emissions System

Check for any of the following conditions:

^ Cracked or punctured EVAP canister.

^ A damaged or disconnected source vacuum line, EVAP purge line, vent hose or fuel tank vapor line.

^ A faulty or erratic fuel tank pressure sensor can cause a DTC P0455 to set.

^ A poor connection at the PCM. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and a poor terminal to wire connection.

^ A damaged wiring harness. Inspect the wiring harness to the EVAP vent solenoid, EVAP canister purge valve, EVAP tank pressure control solenoid vacuum valve and the fuel tank pressure sensor for an intermittent open or shorted circuit.

If a DTC P0455 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was last set.

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. If any other EVAP DTCs except a DTC P0455 are set, diagnose those DTCs first.

6. This step checks the operation of the EVAP tank pressure control solenoid vacuum valve. The EVAP tank pressure control solenoid vacuum valve output control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM. Output controls can be found on the Tech 2 scan tool under Special Functions.

9. If the test light illuminates during this test, the problem may be the result of the control circuit shorted to ground. This will keep the EVAP tank pressure control solenoid vacuum valve open and cause the system to fail. The EVAP tank pressure control solenoid vacuum valve output control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM. Output controls can be found on the Tech 2 scan tool under Special Functions.

10. This step checks the EVAP canister purge valve for leakage.

13. This step checks the operation of the EVAP canister vent solenoid. The EVAP canister vent solenoid output control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM. Output controls can be found on the Tech 2 scan tool under Special Functions.

15. This step checks the EVAP canister vent solenoid control circuit. The EVAP canister vent solenoid output control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM. Output controls can be found on the Tech 2 scan tool under Special Functions.

16. This step determines whether or not the EVAP system is sealed sufficiently to be pressurized. If not, the leak must be located and corrected before continuing with the diagnosis. The EVAP canister vent solenoid output control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM. Output controls can be found on the Tech 2 scan tool under Special Functions.