P0446

DESCRIPTION
A Restricted or Blocked EVAP Vent Path is detected by the Powertrain Control Module (PCM) monitoring the fuel tank pressure during normal operation. The PCM commands the Evaporative Emission (EVAP) vent valve OFF (open), and the EVAP canister purge valve ON (open). The fuel tank pressure should remain low as vacuum is drawn on the EVAP system. If the vent path is blocked or restricted, the vacuum level will increase and DTC P0446 will set.

CONDITIONS FOR RUNNING THE DTC
^ DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0443, P0449, P0452, P0453, P1106, P1107, P1112, P1114, P1115, P1121, or P1122 are not set.
^ The system voltage is between 10-18 volts.
^ The start-up Engine Coolant Temperature (ECT) is between 4-30°C (39-86°F).
^ The start-up Intake Air Temperature (IAT) is between 4-30°C (39-86°F).
^ The fuel tank level is between 30-85 percent.
^ The Barometric Pressure (BARO) is more than 75 kPa.
^ The Vehicle Speed Sensor (VSS) is less than 75 mph.

CONDITIONS FOR SETTING THE DTC
^ Fuel tank pressure is less than -10 inches H2O.
^ The condition is present for as long as 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.

DIAGNOSTIC AIDS
The EVAP system tests run when the engine is first started and meets the Conditions for Running the DTC. 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 condition. To repair a blockage in the EVAP system. Refer to Evaporative Emission (EVAP) System Cleaning. Service and Repair

TEST DESCRIPTION

Steps 5-13:

The number below refers to the step number on the diagnostic table.
4. This test determines if the failure is present or intermittent.