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 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 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. A small leak in the system will cause DTC P0442 to be set.

CONDITIONS FOR RUNNING THE DTC
^ No active MAP sensor DTCs
^ No active TP sensor DTCs
^ No active VSS DTCs
^ No active HO2S DTCs
^ No active ECT sensor DTCs
^ No active 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 (ECT minus IAT) is less than:
1.5°C when the IAT is more than the ECT.

OR

8°C 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 inch 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 MIL during the second key cycle.
^ The VCM stores the conditions that were present when the DTC sets as the Freeze Frame and the Fail 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 DTCs 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 faulty connection at the VCM. Inspect the harness connectors for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Faulty terminal to wire connections
^ A damaged harness: Inspect the wiring harness to the EVAP vent solenoid EVAP purge solenoid and the fuel tank pressure sensor for an intermittent, an open, or a 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 beginning 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 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. Ensure that the valve core is not damaged. If you suspect the service port of leakage, use the following procedure:

Disconnect the purge line from the evaporative emissions (EVAP) purge solenoid valve.

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

Apply vacuum to 5 inches Hg. If the vacuum does not hold, replace the entire purge line that 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 you cannot run the service bay test, proceed to step 5. If a fault is not currently present, the diagnostic table steps will return you to step 3.
9. For the correct set-up and adjustment procedures, refer to the information that is supplied with the EVAP pressure and purge diagnostic cart.
13. An EVAP pressure sensor that does not correctly respond to pressure or to vacuum will cause this DTC to set.

The EVAP pressure sensor monitors a range from 7.5 inches H2O of pressure to -17.5 inch H2O of vacuum.