P0446

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Refer to Emission Hose Routing Diagram, EVAP SYSTEM OVERVIEW. Emission Control Systems

SYSTEM DESCRIPTION
The EVAP system includes the following components:
- The fuel tank.
- The EVAP vent valve.
- The fuel pipes and hoses.
- The fuel fill cap.
- The EVAP vapor pipes.
- The EVAP purge pipes.
- The EVAP canister.
- The EVAP canister purge valve.

A RESTRICTED or BLOCKED EVAP VENT PATH is detected by monitoring fuel tank pressure during normal operation (EVAP vent valve open, EVAP canister purge valve normal). With the EVAP vent valve open, vacuum level in the system should be very low unless the vent path is blocked.

The following conditions will set DTC P0446.
- Faulty EVAP vent valve (stuck closed).
- Plugged kinked or pinched vent hose.
- Shorted EVAP vent valve driver circuit.
- Plugged EVAP canister.

CONDITIONS FOR RUNNING THE DTC
All conditions for P0440 and P0442 have been met and passed.

CONDITIONS FOR SETTING THE DTC
- Fuel tank pressure is less than -10 in. H2O.
- The condition is present for up to 30 seconds.

ACTION TAKEN WHEN THE DTC SETS
- The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
- The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
- If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn the MIL OFF during the third consecutive trip in witch the diagnostic has been run and passed.
- The history DTC will clear when the PCM turns OFF the MIL.
- The DTC can be cleared by using the scan tool.

DIAGNOSTIC AIDS
Inspect for the following conditions:
- Kinked, pinched or plugged vent hose.
- Inspect for charcoal release from the EVAP canister.

IMPORTANT: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

- Poor terminal connection-Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Diagrams.
- Damaged harness-Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Diagrams.
- PCM and engine grounds for clean and secure connections

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

TEST DESCRIPTION
Number(s) below refer to the step number(s) on the Diagnostic Table:
1. The Powertrain On Board Diagnosis (OBD) System Check prompts you to the basic tests and store the Freeze Frame and Failure Records Data on the scan tool if applicable.
5. Tests the EVAP canister purge valve for a small vacuum source during non purge.
7. Tests the EVAP vent valve for a restriction or blockage.