P0442

Diagnostic Chart (Part 1 Of 3):

Diagnostic Chart (Part 2 Of 3):

Diagnostic Chart (Part 3 Of 3):

CIRCUIT DESCRIPTION
The Evaporative Emissions (EVAP) system includes the following components:
^ The fuel tank
^ The EVAP vent valve
^ The fuel tank pressure sensor
^ The fuel pipes and hoses
^ The vapor lines
^ The fuel cap
^ The EVAP canister
^ The purge lines
^ The EVAP purge valve

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 pressure sensor input. At an appropriate time, the EVAP purge valve and the EVAP vent valve 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 valve 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 Heated Oxygen Sensor (HO2S) DTCs
^ No active Engine Coolant Temperature (ECT) sensor DTCs
^ No active Intake Air Temperature (IAT) sensor DTCs
^ DTC P0125 is not active
^ The fuel level is 12.5 - 87 percent
^ The ECT is 4°C - 30°C (39°F - 86°F)
^ The IAT is 4°C - 30°C (39°F - 86°F)
^ The cold start ECT minus IAT is less than the following:
1.5°C when the IAT is more than the ECT
8°C when the ECT is more than the IAT
^ The Barometric Pressure (BARO) is more than 72 kPa
^ The change in the fuel tank vacuum is less than 0.6 inches of H2O, or the change in the 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 more than 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
^ 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 Freeze Frame and 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 DTCs diagnostic table. Always check for fuel level sensor DTCs stored in History.

Physically check for the following conditions:
^ A missing, damaged, incorrect, or improperly installed fuel cap
^ Any missing or damaged O-rings at the EVAP canister fuel vapor and purge line fittings
^ A cracked or punctured EVAP canister
^ Any damaged or disconnected EVAP purge line, vent hose, or fuel tank vapor line
^ Any incorrectly routed or damaged EVAP system purge and vapor lines
^ A poor connection at the VCM. Inspect the harness connectors for the following conditions:
- Any backed-out terminals
- Any improper mating
- Any broken locks
- Any improperly formed or damaged terminals
- Any poor terminal-to-wire connections
^ A damaged harness. Inspect the wiring harness to the EVAP vent valve, the EVAP purge valve, 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 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 valve.

Connect a hand vacuum pump to the service port by placing the hose/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 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 chart 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 inches H2O of pressure to -17.5 inches H2O of pressure.