P0442
DTC P0442 EVAPORATIVE EMISSION CONTROL SYSTEM LEAK DETECTED (SMALL LEAK)CIRCUIT DESCRIPTION
DTC Detecting Condition:
The Evaporative Emissions (EVAP) system is equipped to reduce EVAP in the fuel tank. The EVAP system contains the followings:
- Canister: Stores EVAP that is created in the fuel tank.
- Fuel Tank Pressure (FTP) sensor: Measures the FTP.
- EVAP VSV: Opens and purges EVAP in the EVAP canister into the intake manifold.
ON: open OFF: closed
- Canister Closed Valve (CCV): Introduces atmosphere to the EVAP canister when it opens. The CCV opens under the normal condition.
ON: closed OFF: open
- By-pass VSV: Connects the fuel tank and EVAP canister.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions Part 1:
Typical Enabling Conditions Part 2:
Typical Malfunction Thresholds Part 1:
Typical Malfunction Thresholds Part 2:
The ECM monitors EVAP leak and the components on the EVAP system using a continuous test called the EVAP System Test. The EVAP System Test is done according to the following procedures:
a. The ECM starts the EVAP System Test when the following conditions are met.
- The Engine Coolant Temperature (ECT) and the Intake Air Temperature (IAT) are 10 to 35 °C (50 to 95 °F) when the engine is started (P0455, P0456). The ECT and IAT is 10 to 32 °C (50 to 90 °F) when the engine was started (P0442..
- The difference of the ECT and IAT is -7 to 11 °C (-12.6 to 20 °F) when the engine was started.
- FTP is stabilized.
b. The ECM measures the increase in EVAP (increase in FTP).
c. The ECM closes the CCV to shut out the atmosphere and opens the by-pass VSV to connect the EVAP canister and the fuel tank. Then the ECM opens the EVAP VSV to use the intake manifold's pressure to create a vacuum (negative pressure.in the EVAP canister and fuel tank.
d. If the FTP does not decrease while a vacuum was being introduced (step (C)), the ECM determines that the EVAP VSV is stuck closed.The ECM illuminates the MIL (2 trip detection logic.and sets DTC P0441.
e. The ECM closes the EVAP VSV to seal the EVAP system. The ECM then performs an EVAP leak check by monitoring FTP increase for 5 seconds.
If the FTP increase is larger than the specified value, the ECM interprets this as an EVAP 0.02 inch leak. The ECM illuminates the MIL (2 trip detection logic.and sets DTC P0456.
If the FTP increase is larger than an EVAP 0.02 inch leak, the ECM interprets this as an EVAP 0.04 inch leak. The ECM illuminates the MIL (2 trip detection logic.and sets DTC P0442.
If the FTP does not drop to -2.4 kPa (-18 mmHg) when creation of vacuum (negative pressure.is finished, the ECM interprets this as an EVAP gross leak. The ECM illuminates the MIL (2 trip detection logic.and sets DTC P0455.
f. The ECM opens the CCV to check CCV operation.
If the FTP increase is smaller than the specified value, the ECM determines that the CCV is stuck closed.The ECM illuminates the MIL (2 trip detection logic.and sets DTC P0446.
g. The ECM closes the by-pass VSV to check the by-pass VSV operation.
If the FTP increase is larger than the specified value, the ECM interprets this as a by-pass VSV malfunction. The ECM illuminates the MIL (2 trip detection logic.and sets DTC P2418.
If the FTP is less than the specified value, the ECM determines that the EVAP VSV is stuck open or the CCV is stuck closed.The ECM illuminates the MIL (2 trip detection logic.and sets DTCs P0441 and P0446.
MONITOR RESULT
Refer to Monitor Trips and/or Drive Cycle.
The test value and test limit information are described as shown in the table.Check the monitor result and test values after performing the monitor drive pattern.
- TID (Test Identification Data. is assigned to each emissions-related component.
- TLT (Test Limit Type.: If TLT is 0, the component is malfunctioning when the test value is higher than the test limit. If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
- CID (Component ldentification Data. is assigned to each test value.
- Unit Conversion is used to calculate the test value indicated on generic OBD II scan tools.
CONFIRMATION READINESS TEST
First Trip Procedure
a. The vehicle must be cold and the ambient temperature must be between 10 to 35 °C (50 to 95 °F).
b. The IAT and the ECT have almost the same values.
c. Clear the DTCs .
Enter the following menus: ADVANCED OBD II / ONBOARD TEST / READINESS TESTS. Then the READINESS TEST will show INCMPL (incomplete).
d. Run the vehicle according to the readiness monitor drive pattern. Note the state of the READINESS TEST. They will change to COMPL (complete) as the EVAP evaluation monitors (EVAP EVAL) operate and if the system passes. This procedure may take 20 minutes or more.
NOTE: Do not shut off the engine, as the results will be invalid.
Pass Condition or No Problem Found by the ECM
If EVAP EVAL shows COMPL, go to the NON-CONTINUOUS TEST screen.
Enter the following menus: ADVANCED OBD II / ONBOARD TEST / NON-CONTINUOUS TESTS.
NOTE: Do not shut off the engine, as the results will be invalid.
If all of the tests in the time $02 category show "Pass", EVAP EVAL detected no problems.
Fail Condition - Problem Detected by the ECM
If EVAP EVAL shows INCMPL, go to the NON-CONTINUOUS TEST screen.
Enter the following menus: ADVANCED OBD II / ONBOARD TEST / NON-CONTINUOUS TESTS.
1. If all tests show "Pass", the following may have occurred.
- EVAP EVAL did not operate.
- EVAP EVAL did not finish.
- The ECM withheld judgement.
2. If one or more of the tests in the time $02 category show "Fail", EVAP EVAL did operate and the ECM detected a problem.
3. Go to the CONTINUOUS TESTS screen. This is the only place DTC's are listed for the first trip. Enter the following menus: ADVANCED OBD II/ ONBOARD TEST/ CONTINUOUS TESTS.
NOTE: The DTC listed may not be valid.A second trip is needed to confirm the DTC.
Second Trip Procedure
a. Vehicle must be cold and the ambient temperature must be between 10 to 35 °C (50 to 95 °F).
b. Go to the READINESS TESTS screen.
c. Drive the vehicle according to the readiness monitor drive pattern. Note the state of EVAP EVAL. This procedure may take approximately 20 minutes or more.
NOTE: Do not shut off the engine, as the results will be invalid.
d. If the READINESS TEST changes to COMPL, the EVAP EVAL has operated.Check for any stored DTC's.
- If a DTC has been stored, a problem has been detected and confirmed by the ECM.
- If no DTC was stored, the EVAP monitor operated but no problem was detected.
Wiring Diagram:
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INSPECTION PROCEDURE
HINT:
- Ask the customer whether, after the MIL is illuminated, the customer found the fuel tank cap was loose and tightened it. Also ask the customer whether the fuel tank cap was loose when refuelling.If the fuel tank cap was loose, it was the cause of the DTC. If the fuel tank cap was not loose or if the customer was not sure if it was loose, troubleshoot according to the following procedure.
- Read freeze frame data using the hand-held tester. Freeze frame data records the engine conditions when a malfunction is detected.When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was LEAN or RICH, etc.at the time of the malfunction.