P0446

Diagnostic Chart:

Electrical:

CIRCUIT DESCRIPTION

The evaporative system includes the following components:

^ The Fuel Tank

^ The EVAP Vent Valve

^ The Fuel Tank Pressure sensor

^ The Fuel Pipe and hoses

^ The Vapor Lines

^ The Fuel Cap

^ The EVAP Canister

^ The Purge Line

^ The EVAP Purge Solenoid

The following items detect a restricted or blocked EVAP Canister vent path:

^ Drawing a vacuum into the EVAP system

^ Turning OFF the EVAP Vent Valve and the EVAP Purge Solenoid (EVAP Vent Valve Open, the EVAP Purge Solenoid PWM 0%)

^ Monitoring the Fuel Tank Pressure sensor input With the EVAP Vent Valve open, any vacuum in the system should decrease quickly unless the vent path is blocked. The following conditions can cause a blockage:

^ A malfunctioning EVAP Vent Valve (stuck closed)

^ A plugged kinked or pinched vent hose

^ A shorted EVAP Vent Valve Driver circuit

^ A plugged EVAP Canister.

If any of these conditions are present, a DTC P0446 set.

CONDITIONS FOR SETTING THE DTC

The following conditions will set the DTC:

^ No MAP sensor DTCs

^ No TP sensor DTCs

^ No VSS DTCs

^ No HO2S DTCs

^ No ECT DTCs

^ DTC P0125 not active

^ No IAT sensor DTCs

^ No Fuel Level DTCs

^ The ECT is greater than 3.75°C (38.75°F) but less than 30°C (86°F)

^ The IAT is greater than 3.75.°C (38.75°F) but less than 30°C (86°F)

^ Start up ECT is not more than 8.25°C (46.85°F) greater than the start up IAT

^ Start up IAT is not more than 1.5°C (34.7°F) greater than the start up ECT

^ The Fuel Level is greater than 10% and 85%

^ The Baro is greater than 72.5 kPa

^ The System Voltage is greater than 10 volts but less than 17 volts

^ Excess vacuum present in the EVAP system

ACTION TAKEN WHEN THE DTC SETS

^ The VCM illuminates the MIL during the first key cycle in which the DTC sets.

^ The VCM stores the conditions which were present when the DTC sets as a Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The MIL will turn OFF after one ignition cycle in which the diagnostic runs without a fault.

^ The Freeze Frame information and the history DTC will clear after one ignition cycle in which the diagnostic runs without a fault.

^ A scan tool can clear the DTC(s).

DIAGNOSTIC AIDS

Check for the following conditions:

^ A poor connection at the VCM: Inspect the harness connectors for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed or damaged terminals

- Poor terminal to wire connection.

^ A damaged harness: Inspect the wiring harness to the EVAP Vent Valve, EVAP Purge Solenoid and the Fuel Tank Pressure sensor for an intermittent open or short circuit.

^ A kinked, pinched or plugged vent hose. Verify that the vent hose between the EVAP Canister and the EVAP Vent Valve is not restricted.

Refer to EVAP Control System Diagnosis before starting repairs. System Diagnosis - EVAP Control

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

TEST DESCRIPTION

The numbers below refer to the step numbers in the diagnostic table.

2. This step checks the Fuel Tank Pressure sensor at atmospheric pressure.

3. This step verifies that the Fuel Tank Pressure sensor accurately reacts to EVAP system pressure changes.

5. Checks for a blocked EVAP Canister.