P0442

Diagnostic Chart:

Electrical:

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:

^ 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

^ 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 equals true.

^ The fuel level present test equals true.

Fuel Slosh Test

Tank vacuum is greater than 0.6 in of H2O 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 greater than or equal to 9 inches of H2O within 12.5 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 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:

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

^ A cracked or punctured EVAP canister

^ A loose, damaged or misaligned fuel filler tube or fuel filler vent hose

^ 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 EVAP Control System Diagnosis before starting the 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 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.