For 1990-2009 cars

### DTC Descriptor

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

### Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

### Circuit/System Description

The control module tests the evaporative emission (EVAP) system for a large leak. 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.

FTP Sensor Signal Voltage | Fuel Tank Pressure
--- | ---
High, Approximately 1.5 Volts or More | Negative Pressure/Vacuum
Low, Approximately 1.5 Volts or Less | Positive Pressure

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

Control Module Command | EVAP Canister Purge Valve | EVAP Canister Vent Valve
--- | --- | ---
ON | Open | Closed
OFF | Closed | Open

### Conditions for Running the DTC

• | Before the engine control module (ECM) can report DTC P0455 failed, DTCs P0443, P0451, P0452, P0453, P0458, and P0459 must run and pass.

• | DTCs P0100, P0101, P0102, P0103, P0111, P0112, P0113, P116, P0117, P0118, P0119, P0125, P0443, P0446, P0449, P0451, P0452, P0453, P0458, P0459, P0496, P0498, P0499, P0560, P0562, P0563, P0721, P0722, P2122, P2123, P2127, P2128, P2138, P2227, P2228, and P2229 are not set.

• | The ignition voltage is between 10.5-18 volts.

• | The engine run time is more than 10 minutes or the fuel trim is stable.

• | The fuel tank pressure is between -10.0 and +4.0 in. H2O (-18.7 and 7.49 mm Hg).

• | The fuel system is operating in Closed Loop.

• | The engine is idling.

• | The barometric pressure (BARO) is more than 68 kPa.

• | The fuel level is between 12-88 percent.

• | The calculated ambient air temperature is between 2-32°C (35-90°F).

• | The coolant temperature at engine start is within 10°C (18°F) of the calculated ambient air temperature.

• | The vehicle speed sensor (VSS) is less than 3 km/h (2 mph).

• | The above conditions are met for more than 11 seconds.

• | DTC P0455 will attempt to run up to 10 times or the test completes successfully once per ignition cycle.

### Conditions for Setting the DTC

• | The ECM detects the EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

• | The condition exists for more than 4 seconds.

### Action Taken When the DTC Sets

DTC P0455 is a Type A/B DTC.

### Conditions for Clearing the DTC

DTC P0455 is a Type A/B DTC.

### Diagnostic Aids

• | A fuel fill cap that is left OFF after a fuel fill, will cause this DTC to set.

• | A loose, missing, or damaged fuel fill cap can cause this DTC to set.

• | A blockage or restriction in the EVAP purge solenoid, purge pipe EVAP canister, or vapor pipe, can cause this DTC to set.

• | 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 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.

• | 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.

### Reference Information

#### Schematic Reference

Evaporative Emissions Hose Routing Diagram

#### Description and Operation

Evaporative Emission Control System Description

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

#### Special Tools Required

• | J 41413-SPT High Intensity White Light

• | J 41413-VLV EVAP Port Vent Fitting Tool

• | J 41413-200 Evaporative Emissions System Tester (EEST)

• | J 41413-300 EVAP Cap and Plug Kit

• | CH-48096 EVAP Service Port Access Tool

• | GE-41415-50 Fuel Tank Cap Adapter

### Circuit/System Verification

1. Verify the following conditions do not exist in the EVAP system:

• | Loose, incorrect, missing, or damaged fuel fill cap

• | Loose, missing, or damaged service port schrader valve (if equipped)

• | Loose or damaged fuel tank pressure (FTP) sensor.

• | A damaged EVAP purge solenoid

• | Disconnected, incorrectly routed, kinked, or damaged EVAP pipes and hoses

• | A damaged EVAP vent valve or EVAP canister

⇒ | If you find any of the above conditions, repair as necessary.

Important: Refer to the J 41413-200 operation manual for detailed instructions.

2. Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
3. Calibrate the J 41413-200 Flow Meter to the correct leak orifice for the vehicle.
4. Command the EVAP vent solenoid closed with a scan tool.

Important: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.

5. Activate the J 41413-200 and compare the flow meter's stable floating indicator position to the red flag. The floating indicator should be below the red flag.

⇒ | If the floating indicator is above the red flag, test for a leak in the EVAP system.

⇒ | If the floating indicator is below the red flag, test for a blockage or restriction in the EVAP system.

6. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

#### Leak Testing

Important:

• | You must start with the Circuit/System Verification before proceeding with Circuit/System Testing.

• | Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. The system flow will be less with higher temperatures.

1. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
2. Turn the nitrogen/smoke valve on the control panel to SMOKE.
3. Command the EVAP vent solenoid closed with a scan tool.
4. Use the remote switch to introduce smoke into the EVAP system.
5. Use the J 41413-VLV to open the EVAP service port, if equipped. Or, disconnect the EVAP purge pipe from the purge solenoid. Once smoke is observed, remove the tool, or reconnect the EVAP purge pipe.

Important: Introduce smoke at 15 second intervals while testing the system.

6. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .

Important: The fuel tank may need to be lowered to improve visibility of some of the EVAP system components.

⇒ | If smoke is observed, repair the condition as necessary.

7. Verify the EVAP system using the EVAP service port. Connect the J 41413-200 nitrogen/smoke supply hose to the EVAP service port. Connect the CH-48096 EVAP Service Port Access Tool between the EVAP purge solenoid and the EVAP purge pipe, if necessary.
8. Command the EVAP vent solenoid closed with a scan tool.
9. Use the remote switch to introduce smoke into the EVAP system.

Important: The fuel tank may need to be lowered to improve visibility of some of the EVAP system components.

10. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .

⇒ | If smoke is observed, repair the condition as necessary.

Important: The fuel tank may need to be lowered to improve visibility of some of the EVAP system components.

11. Verify the individual EVAP system components for a leak using the J 41413-300 .

⇒ | If a condition is found replace the affected component.

#### Blockage/Restriction Testing

1. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
2. Disconnect the EVAP vent line from the vent solenoid, and seal it, using the correct plug from the J 41413-300 .
3. Pressurize the EVAP system with nitrogen to 5 inches H20. Compare the Fuel Tank Pressure Sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H20 of the pressure/vacuum gage.

⇒ | If the FTP sensor parameter is not within 1 inch H20 of the pressure/vacuum gage, replace the FTP sensor.

4. Increase the EVAP purge solenoid to 100 percent. The FTP sensor pressure should drop to less than 1 in H2O.

⇒ | If the FTP sensor parameter is greater than 1 in H2O, disconnect the EVAP pipes listed below one at a time while observing the FTP sensor parameter with a scan tool. If the FTP sensor parameter drops to less than 1 in H2O when a pipe is disconnected, repair the blockage or restriction in the one of the following EVAP pipe/hoses:

4.1. | EVAP purge vacuum source from the EVAP purge solenoid

4.2. | EVAP purge pipe from the EVAP purge solenoid

4.3. | EVAP purge pipe at the EVAP canister

4.4. | EVAP vapor pipe at the EVAP canister

5. If you cannot locate a condition with the EVAP system, refer to Diagnostic Aids for additional information.

### Component Testing

1. Pressurize the EVAP system to 5 inches H20.
2. Compare the Fuel Tank Pressure sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H20 of the pressure/vacuum gage.
3. Command the EVAP vent valve open with a scan tool.
4. The scan tool Fuel Tank Pressure parameter should be 0 inches H20.

⇒ | If the FTP sensor parameters do not respond to the change in pressure, replace the FTP sensor.

### Repair Instructions

• | Fuel Tank Pressure Sensor Replacement

• | Evaporative Emission Canister Purge Solenoid Valve Replacement

• | Evaporative Emission Canister Vent Solenoid Valve Replacement

• | Evaporative Emission Pipe Replacement

• | Evaporative Emission Canister Replacement

### Repair Verification

1. Turn the nitrogen/smoke valve to nitrogen.
2. Command the EVAP vent valve closed with a scan tool.
3. Use the remote switch to activate the J 41413-200 .
4. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating indicator stabilizes.
5. Verify the flow meter's stable floating indicator position is at or below the red flag.
6. Clear the DTCs with a scan tool.