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Home >> Chevrolet >> 2006 >> Optra (CANADA) L4-2.0L >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0456

P0456




DTC P0442 or P0456

DTC Descriptors
DTC P0442
- Evaporative Emission (EVAP) System Small Leak Detected

DTC P0456
- Evaporative Emission (EVAP) System Very Small Leak Detected

Circuit Description

The evaporative emission (EVAP) small leak test applies vacuum to the EVAP system and monitors vacuum decay. The control module monitors the fuel tank pressure sensor signal to determine the vacuum decay rate. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned ON. This allows the engine to draw vacuum on the EVAP system. After the desired vacuum level has been achieved, the EVAP purge valve is turned OFF, sealing the system. A leak is detected by monitoring for a decrease in the vacuum level during a given time period. If the system detects a leak larger than a calibrated amount, DTC P0442 or DTC P0456 will set.

Diagnostic Fault Information

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





Conditions for Running the DTC

* Before the engine control module (ECM) can report DTC P0442, or DTC P0456 failed, DTC P0441 must run and pass.
* DTCs P0106, P0107, P0108, P112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0137, P0138, P0140, P0141, P0201, P0202, P0203, P0204, P0402, P0404, P0405, P0406, P0443, P0452, P0453, P0462, P0463, P0488, P0502, P2195, and P2196 are not set.
* The ignition 1 voltage is between 11-16 volts.
* The barometric pressure (BARO) is more than 72 kPa.
* The start-up intake air temperature (IAT) minus the start-up engine coolant temperature (ECT) is less than 12°C (53°F).
* The start-up ECT minus start-up IAT is less than 50°C (122°F).
* The start-up ECT and IAT is between -5 to +40°C (+41 to +104°F).
* The start-up IAT is 3°C (37°F) less than the actual IAT.
* Purge start time is less than 360 seconds.
* Engine run time is more than 1 second and less than 420 seconds plus purge start time.
* The DTCs run once an ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The EVAP system can achieve vacuum but a vacuum decay is detected during the diagnostic test.

Action Taken When the DTC Sets

DTC P0442 is a Type A/B DTC.

DTC P0456 is a Type A/B DTC.

Conditions for Clearing the DTC

DTC P0442 is a Type A/B DTC.

DTC P0456 is a Type A/B DTC.

Diagnostic Aids

* To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
* To help locate intermittent leaks, use the J 41413-200 to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT . 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.
* 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 Electrical Diagrams

Connector End View Reference
* Engine Control Module (ECM) Connector End Views Engine Control Module (ECM) Connector End Views
* Engine Controls Connector End Views Engine Controls Connector End Views

Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
* Scan Tool Data List Scan Tool Data List
* Scan Tool Data Definitions Scan Tool Data Definitions
* Scan Tool Output Controls 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

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
* 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 EEST 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 EEST and compare the flow meter's stable floating indicator position to 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 an intermittent condition. Refer to Diagnostic Aids.

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 Data List.

Circuit/System Testing

Important: 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. Turn the nitrogen/smoke valve on the control panel to SMOKE.
2. Command the evaporative emission (EVAP) vent solenoid closed with a scan tool.
3. Use the remote switch to introduce smoke into the EVAP system.
4. Use the J 41413-VLV to open the EVAP service port. Once smoke is observed, remove the tool.

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


5. Verify the entire EVAP system with the J 41413-SPT . Smoke should not be observed.

• If smoke is observed, repair the condition as necessary.

• If smoke is not observed, verify the EVAP system using the EVAP service port.

6. Connect the EEST nitrogen/smoke supply hose to the EVAP service port.
7. Command the EVAP vent solenoid closed with a scan tool.
8. Use the remote switch to introduce smoke into the EVAP system.
9. Verify the entire EVAP system with the J 41413-SPT . Smoke should not be observed.

• If smoke is observed, repair the condition as necessary.
• If smoke is not observed, test the individual EVAP system components for a leak using the J 41413-300 .

Repair Instructions

* Evaporative Emission (EVAP) Canister Replacement Service and Repair
* Evaporative Emission (EVAP) Canister Purge Solenoid Valve Replacement Service and Repair
* PSD SIE TITLE Error: SIE linked to empty Cell ID 125178
* Evaporative Emission (EVAP) System Hoses/Pipes Replacement Service and Repair
* Fuel Tank Pressure Sensor Replacement Service and Repair

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. Compare the flow meter's stable floating indicator position to the red flag.
6. Clear the DTCs with a scan tool.

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