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, P0116, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0135, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0300, P0402, P0404, P0405, P0406, P0443, P0451, P0452, P0453, P0454, P0461, P0462, P0463, P0464, P0488, P0498, P0499, P0502, P0506, P0507, P2110, P2195, and P2196 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 (46°F).

• | The ignition 1 voltage is between 11-16 volts.

• | The barometric pressure (BARO) is greater than 72 kPa.

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

• | The start-up IAT is 3°C (37°F) less than the actual IAT.

• | The purge enable time is less than pre-determined value based on startup ECT.

• | The fuel level is between 6-93 percent.

• | The engine run time is between 1-360 seconds plus purge enable time.

• | The engine is idling.

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

• | The throttle position is less than 1 percent.

• | The manifold absolute pressure (MAP) sensor is steady within than 5 kPa.

• | 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 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 High Intensity White Light.

• | A condition may exist where a leak in the EVAP system exists only under a vacuum condition. Test for this condition by using a scan tool Purge/Seal function to create a vacuum, then observe the FTP parameter for a vacuum decay.

• | 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

Engine Controls Schematics

#### 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

• | GE-41415-50 Fuel Tank Cap Adapter

• | J 23738-A Vacuum Pump

### Circuit/System Verification w/Service Bay Test

Important: Verify the EVAP vent valve functions before proceeding with this diagnostic. You should hear or feel a click when commanded ON with a scan tool. A circuit condition can cause the solenoid to be inoperative without setting a DTC P0448, or a DTC P0449. Refer to DTC P0498 or P0499

1. Verify the EVAP system using the scan tool EVAP Service Bay Test. DTC P0455 should not set.
2. 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 Verification w/o Service Bay Test

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

• | 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:

• | Verify the EVAP vent valve functions before proceeding with this diagnostic. You should hear or feel a click when commanded ON with a scan tool. A circuit condition can cause the solenoid to be inoperative without setting a DTC P0448, or a DTC P0449. Refer to DTC P0498 or P0499

• | Refer to the J 41413-200 Evaporative Emissions System Tester (EEST) 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 EEST Flow Meter to the correct leak orifice for the vehicle.

Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.

4. Disconnect the EVAP vent line from the vent solenoid. Seal the EVAP vent using the correct plug from the J 41413-300 .

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 remain below the red flag.
6. Increase the EVAP purge solenoid to 100 percent. The FTP sensor pressure should drop to less than 1 in H2O. If the floating indicator is below the red flag, test for a blockage or restriction in the EVAP system.
7. 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 Data 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.

Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.

3. Disconnect the EVAP vent line from the vent solenoid. Seal the EVAP vent using the correct plug from the J 41413-300 .
4. Use the remote switch to introduce smoke into the EVAP system.
5. Use the EVAP Port Vent Fitting tool to open the EVAP service port. Once smoke is observed, remove the tool.

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.

Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.

8. Disconnect the EVAP vent line from the vent solenoid. Seal the EVAP vent using the correct plug from the J 41413-300 .
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 . The EVAP system components should not leak.

⇒ | 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 .

Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.

2. Disconnect the EVAP vent line from the vent solenoid. Seal the EVAP vent 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 EEST 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. Disconnect the EVAP vent line from the vent solenoid.
2. With a scan tool command the EVAP vent solenoid valve ON, (closed).
3. With a hand held vacuum pump, apply vacuum to the EVAP vent solenoid valve port. The vacuum should not decrease

⇒ | If the vacuum decreases, replace the EVAP vent solenoid valve.

### Repair Instructions

• | Fuel Tank Pressure Sensor Replacement

• | Evaporative Emission Canister Purge Solenoid Valve Replacement

• | Evaporative Emission System Hoses/Pipes Replacement

• | Evaporative Emission Canister Replacement

### Repair Verification w/Service Bay Test

Verify the EVAP system repair using the EVAP Service Bay Test

### Repair Verification w/o Service Bay Test

1. Turn the nitrogen/smoke valve to nitrogen.

Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.

2. Disconnect the EVAP vent line from the vent solenoid. Seal the EVAP vent using the correct plug from the J 41413-300 .
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.