For 1990-2009 cars

### Diagnostic Instructions

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

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

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

### 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. If the system is unable to achieve the calibrated vacuum level, or the vacuum level increases too slowly, this DTC sets.

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

• | DTCs P0106, P0107, P0108, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0222, P0223, P0204, P0443, P0449, P0452, P0453, P0454, and P0502 are not set.

• | One of the following conditions is met:

- | The ignition is off for greater than 12 hours.

- | OR

- | The start-up intake air temperature (IAT) and the start-up engine coolant temperature (ECT) are within 8°C (14°F).

• | The ignition voltage is between 11-18 volts.

• | The barometric pressure (BARO) is greater than 70 kPa.

• | The start-up ECT and start-up IAT are between 4-34°C (39-93°F).

• | The start-up IAT is 3°C (5°F) less than the actual IAT.

• | The EVAP purge is greater than 2 percent.

• | The fuel level is between 10-90 percent.

• | The engine run time is less than 17 minutes.

• | The DTC run once an ignition cycle when the above conditions are met.

### Conditions for Setting the DTC

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

### Action Taken When the DTC Sets

DTC P0455 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P0455 is a Type 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 .

• | The EVAP system can also be tested from the front of the vehicle using the CH-48096 .

• | 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

Control Module References for scan tool information

#### Special Tools

• | J 41413-SPT High Intensity White Light

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

• | 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

• | 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.

2. Ignition ON, command the EVAP purge solenoid to 50 percent with a scan tool. You should hear the solenoid click when commanded to 50 percent.

⇒ | If the solenoid does not click, refer to DTC P0443 for further diagnosis.

3. Command the EVAP vent solenoid ON and OFF with a scan tool. You should hear the solenoid click when commanded ON and OFF.

⇒ | If the solenoid does not click, refer to DTC P0449 for further diagnosis.

4. Engine idling, command the EVAP purge solenoid to 50 percent while observing the scan tool FTP sensor pressure parameter. The reading should indicate a vacuum.

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

5. Ignition OFF, 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 .
6. Calibrate the J 41413-200 Flow Meter to the correct leak orifice for the vehicle.
7. Turn the nitrogen/smoke valve on the control panel to nitrogen.

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

8. Use the remote switch to 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.
9. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

Note:

• | 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. Install the fuel fill cap. Engine idling, command the EVAP purge solenoid to 50 percent while observing the FTP sensor pressure parameter. The reading should indicate a vacuum.

⇒ | If no vacuum is indicated perform the following:

1.1. | Ignition OFF, disconnect the EVAP purge pipe from the EVAP purge solenoid.

1.2. | Engine idling, command the EVAP purge solenoid to 50 percent. Verify vacuum is available to the EVAP purge pipe.

⇒ | If no vacuum is available, test the vacuum supply hose for a restriction. If the hose tests normal, replace the EVAP purge solenoid.

⇒ | If vacuum is available, test the EVAP purge pipe between the EVAP purge solenoid and the fuel tank for a restriction. If the pipe tests normal, replace the FTP sensor.

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. Turn the nitrogen/smoke valve on the control panel to SMOKE.
4. Ignition ON, command the EVAP vent solenoid ON with a scan tool.

Note:

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

• | Introduce smoke at 15 second intervals while testing the system.

• | The fuel sender may need to be accessed to inspect some of the EVAP system components.

5. Use the remote switch to introduce smoke into the EVAP system.
6. Verify that smoke is not exiting the entire EVAP system with the J 41413-SPT .

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Evaporative Emission Canister Vent Solenoid Valve Replacement

• | Evaporative Emission Canister Replacement

• | Evaporative Emission Canister Purge Solenoid Valve Replacement

• | Fuel Tank Pressure Sensor Replacement