P0446

DESCRIPTION
A restricted or blocked Evaporative Emission (EVAP) vent path is detected by the Powertrain Control Module (PCM) monitoring the fuel tank pressure during normal operation. The PCM commands the EVAP vent valve OFF, or open, and the EVAP canister purge valve ON, or 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
^ DTC P0107. P0108, P0110, P0112, P0113, P0115, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0443, P0449, P0452, P0453, P1106. P1107, P1111, P1112, P1114, P1115, P1121, and P1122 are not set.
^ The system voltage is between 10-18 volts.
^ The startup Engine Coolant Temperature (ECT) is between 4-30°C (39-86°F).
^ The startup 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
^ The Fuel Tank Pressure (FTP) is less than -10 inches H2O.
^ The condition is present for as long as 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.

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, by a temporary blockage at the EVAP vent valve inlet, or by a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem. In order to repair a blockage in the EVAP system, refer to Evaporative Emission (EVAP) System Cleaning. Service and Repair

TEST DESCRIPTION

Steps 1-3:

Steps 4-13:

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