P0442

Diagnostic Chart (Part 1 Of 3):

Diagnostic Chart (Part 2 Of 3):

Diagnostic Chart (Part 3 Of 3):

Schematic:

CIRCUIT DESCRIPTION
The evaporative system includes the following components:
^ The fuel tank
^ The Evaporative Emission (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 rate. The Vehicle Control Module (VCM) monitors vacuum level via the fuel tank pressure 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. A small leak in the system will cause DTC P0442 to be set.

CONDITIONS FOR RUNNING THE DTC
^ No active Manifold Absolute Pressure (MAP) sensor DTCs
^ No active Throttle Position (TP) sensor DTCs
^ No active Vehicle Speed Sensor (VSS) DTCs
^ No active Oxygen (O2) sensor DTCs
^ No active Engine Coolant Temperature (ECT) sensor DTCs
^ No active Intake Air Temperature (IAT) sensor DTCs
^ DTC P0125 not active
^ The fuel level is between 12.5 percent and 87 percent.
^ The ECT is between 4°C and 30°C (39°F to 86°F).
^ The IAT is between 4°C and 30°C (39°F to 86°F).
^ The cold start temperature difference, which is the ECT minus the IAT, is less than:
1.5°C (35°F) when the IAT is more than the ECT

OR

8°C (46°F) when the ECT is more than the IAT
^ The BARO is more than 72 kPa.
^ The change in fuel tank vacuum is less than 0.6 in. of H2O, or the change in fuel level is less than 8 percent.
^ The throttle position is less than 75 percent.
^ The vehicle speed is less than 65 mph.
^ The fuel tank vacuum level remains above a calibrated value for a specified number of seconds.

CONDITIONS FOR SETTING THE DTC
The EVAP system is unable to hold a specified vacuum level for a calibrated number of seconds.

ACTION TAKEN WHEN THE DTC SETS
^ This is a type A DTC that behaves like a B type, in which the VCM illuminates the Malfunction Indicator Lamp (MIL) during the second key cycle.
^ The VCM stores the conditions that were present when the DTC sets as the Freeze Frame and the Failure Records data.

CONDITIONS FOR CLEARING THE MIL OR DTC
^ The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
^ Use a scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS

IMPORTANT: An accurate indication of fuel level is required for the VCM to properly Pass or Fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTC diagnostic table. Always check for fuel level sensor DTCs stored in History.

Physically check for the following conditions:
^ A loose, missing, damaged, incorrect, or improperly installed fuel cap
^ Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings
^ A cracked or punctured EVAP canister
^ A damaged or disconnected EVAP purge line, vent hose, or fuel tank vapor line
^ Incorrectly routed or damaged EVAP system purge and vapor lines
^ 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 solenoid, EVAP purge solenoid, and the fuel tank pressure sensor for an intermittent, open, or short circuit
^ A kinked, pinched, or plugged vacuum source, EVAP purge, or fuel tank vapor line - Verify that the lines are not restricted.

Refer to Evaporative Emission (EVAP) System Cleaning before starting repairs.

Reviewing the Failure 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 on the diagnostic table.
3. Inspect the service port. Make sure that the valve core is not damaged. If the service port is suspect of leakage use the following procedure:

Disconnect the purge line from the EVAP purge solenoid valve.

Connect a hand vacuum pump to the service port by placing the hose or adaptor over the unthreaded end portion of the service port.

Apply vacuum to 5 in. Hg. If the vacuum does not hold, replace the entire purge line which contains the service port.
4. If the vehicle passes the Service Bay Test then an intermittent leak had occurred. Check the fuel tank cap for a possible loose or leaking condition that may have caused this DTC to set.

If the Service Bay Test can not be run, proceed to step 5. If a fault is not currently present, the diagnostic table steps will return you to step 3.
9. Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures. Testing and Inspection
13. An EVAP pressure sensor that does not correctly respond to pressure or vacuum will cause this DTC to set.

The EVAP pressure sensor monitors a range from +7.5 in. H2O of pressure to -17.5 in. H2O of pressure or vacuum.