P0442

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The evaporative system includes the following components:

^ The fuel tank

^ The EVAP vent solenoid

^ The fuel tank pressure sensor

^ The fuel pipes and hoses

^ The vapor lines

^ The fuel cap

^ The evaporative emission canister

^ The purge lines

^ The EVAP purge solenoid

The evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay. The VCM monitors vacuum level via the fuel tank vacuum sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid turns OFF, sealing the system. A leak is detected by monitoring for a decrease in the vacuum level over a given time period with all other variables remaining constant. A small leak in the system will cause DTC P0442 to be set.

CONDITIONS FOR SETTING THE DTC

The following conditions will set the DTC:

Test Enable

1. No MAP sensor DTCs

2. No TP Sensor DTCs

3. No VSS DTCs

4. No O2S DTCs

5. No ECT DTCs

6. The DTC P0125 not active

7. No IAT sensor DTCs

8. The Fuel Level is greater than 12.5% but less than 87.5%

Cold Start Test

^ 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 BARO is greater than 72.5 kPa.

^ The fuel level input is true

^ The fuel level present test is true

Fuel Slosh Test

Tank vacuum change is less than 0.6 in of H20 or fuel level is greater than 7.8%.

Weak Vacuum Test

^ Throttle Position is less than 75%.

^ Vehicle speed is less than 65 mph.

^ Tank vacuum is at least 9 inches of H20 within 30 seconds.

ACTION TAKEN WHEN THE DTC SETS

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

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

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.

^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery feed for 30 seconds.

DIAGNOSTIC AIDS

Check for the following conditions:

^ Damaged O-rings at the EVAP canister fuel vapor and purge line fittings

^ A cracked or punctured EVAP canister

^ A damaged source vacuum line, an EVAP purge line, a vent hose or fuel tank vapor line

^ 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

- A poor terminal to wire connection

^ A damaged harness: Inspect the wiring harness to the EVAP vent solenoid EVAP purge solenoid and the fuel tank pressure sensor for an intermittent open or short circuit.

^ A missing or damaged weather-pack on the EVAP Purge Solenoid connector.

Refer to Carbon Particle Removal from EVAP System before starting the repairs.

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

TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table

3. This step checks the fuel tank pressure sensor at atmospheric pressure.

4. This step checks the EVAP System for a small leak.