P0446
DTC P0446
DTC DESCRIPTOR
DTC P0446
Evaporative Emissions (EVAP) Vent System Performance
DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection
CIRCUIT/SYSTEM DESCRIPTION
A restricted or blocked evaporative emission (EVAP) vent path is detected by the control module commanding the purge valve ON (open) and the vent valve ON (closed) allowing a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the purge valve OFF (closed) and the vent valve OFF (open) while monitoring the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, DTC P0446 will set.
The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent valves.
CONDITIONS FOR RUNNING THE DTC
- Before the engine control module (ECM) can report DTC P0446 failed, DTCs P0441, P0442, and P0456 must run and pass.
- DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0137, P0138, P0140, P0141, P0261,P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0402, P0404, P0405, P0406, P042E, P0444, P0445, P0452, P0453, P0462, P0463, P0502, P1137, and P1138 are not set.
- The ignition 1 voltage is between 10-16 volts.
- The barometric pressure (BARO) is more than 72 kPa.
- The start-up intake air temperature (IAT) minus the startup engine coolant temperature (ECT) is less than 12°C (53°F).
- The start-up ECT minus startup IAT is less than 50°C (122°F).
- The start-up ECT and IAT is between 0-40°C (32-104°F).
- The start-up IAT is 3°C (37°F) less than the actual IAT.
- The purge start time is less than 360 seconds.
- The engine is OFF for more than 720 minutes or the difference between the IAT and the ECT sensor is less than 12°C (21°F).
- The engine run time is more than 1 second and less than 420 seconds plus purge start time.
- DTC P0446 runs once an ignition cycle when the above conditions are met.
CONDITIONS FOR SETTING THE DTC
- The fuel tank pressure is more than 8 inches H2O at cold engine startup.
- The above condition is present for at least 2 seconds.
ACTION TAKEN WHEN THE DTC SETS
DTC P0446 is a Type A DTC.
CONDITIONS FOR CLEARING THE DTC
DTC P0446 is a Type A DTC.
DIAGNOSTIC AIDS
An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
CIRCUIT/SYSTEM TESTING
1. Verify DTCs P0458, P0459, P0498, P0499, P0452, or P0453 are not set.
- If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
2. Disconnect the purge line from the EVAP purge valve.
3. Ignition ON, observe the fuel tank pressure sensor parameter with a scan tool. The FTP sensor parameter should be 0 inches H2O. If the pressure is not at 0 inches H2O, verify the FTP sensor voltage is less than 4.7 volts.
- If the FTP sensor voltage is more than 4.7 volts, refer to DTC P0452 or P0453. P0452 P0453
4. Reconnect all previously disconnected EVAP hardware.
5. Remove the fuel fill cap and connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50.
IMPORTANT: Refer to the J 41413-200 Evaporative Emissions System Tester (EEST) operation manual for detailed instructions.
6. Ignition ON, engine OFF, seal the EVAP system with a scan tool.
7. Turn the nitrogen/smoke valve on the J 41413-200 to nitrogen.
8. Use the remote switch to activate the J 41413-200 and pressurize the fuel tank with nitrogen to 5 inches H20.
IMPORTANT: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
9. While observing the FTP sensor parameter with a scan tool, command the EVAP vent valve OFF. Verify the FTP Sensor parameter is 0 inches H2O.
- If not test for a blockage or a restriction in the EVAP vent hose, or replace the EVAP vent solenoid valve.
10. 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.
REPAIR INSTRUCTIONS
Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement
REPAIR VERIFICATION
1. Ignition ON, engine OFF, seal the EVAP system with a scan tool.
2. Turn the nitrogen/smoke valve on the J 41413-200 to nitrogen.
3. Use the remote switch to activate the J 41413-200 and pressurize the fuel tank with nitrogen to 5 inches H20.
IMPORTANT: DO NOT exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
4. While observing the FTP sensor parameter with a scan tool, command the EVAP vent valve OFF.
5. Verify the FTP Sensor parameter is 0 inches H2O.