P0442

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Refer to Emission Hose Routing Diagram, EVAP SYSTEM OVERVIEW. Emission Control Systems

SYSTEM DESCRIPTION
The EVAP system includes the following components:
- The fuel tank.
- The EVAP vent valve.
- The EVAP canister purge valve.
- The EVAP Canister.
- The fuel pipes and hoses.
- The EVAP vapor and purge pipes.
- The EVAP fresh air vent hose.
- The fuel fill cap.

The EVAP SMALL LEAK TEST is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP canister purge valve and the EVAP vent valve are turned on allowing 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 is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system will cause DTC P0442 to be set.

CONDITIONS FOR RUNNING THE DTC
- DTC P0443 or P0449 not active.
- No TP, IAT, FTP, ECT or MAP sensor DTCs set.
- System voltage is between 10 and 18 volts.
- The DTC P0440 diagnostic test has passed.
- Startup ECT is not more than 4°C 30°C (39°F - 86°F).
- Startup ECT is not more than 8°C (14°F) greater than IAT start-up temperature.
- Startup IAT not more than 4°C - 30°C (39°F - 86°F).
- Startup IAT is not more than 3°C (7°F) greater than ECT start-up temperature.
- Fuel tank level is between 15% and 85% for a 0.040-0.060 leak.
- Fuel tank level is between 30% and 85% for a 0.020 leak..
- BARO is greater than 75kPa.
- IAT is less than 30°C (86°F)
- VSS below 80 MPH.

CONDITIONS FOR SETTING THE DTC
A vacuum decay condition indicating a small leak is detected during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETS
- The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the first trip in which the diagnostic test has been run and failed.
- The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn the MIL OFF during the first trip in which the diagnostic has been run and passed.
- The history DTC will clear when the PCM turns off the MIL.
- The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
The following conditions will set DTC P0442:
- Loose or malfunctioning fuel fill cap.
- Damaged EVAP purge or vapor pipes.
- Damaged EVAP fresh air vent hose.
- Malfunctioning EVAP vent valve.
- Damaged EVAP Canister.
- Leaking fuel tank, fuel sender assembly O-ring or pressure relief valve.
- Leaking fuel filler neck or seal.

IMPORTANT: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

- Poor terminal connection-Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Diagrams.
- Damaged harness-Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Diagrams.
- PCM and engine grounds for clean and secure connections

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

TEST DESCRIPTION
Number(s) below refer to the step number(s) on the Diagnostic Table:
1. The powertrain On Board Diagnostic (OBD) System Check prompts you to complete some of the basic tests and store the Freeze Frame and Failure Records data on the scan tool if applicable.
15. The EVAP station is pressurizing a sensor that normally reads vacuum. The scan tool reads high pressure at 0 volts and high vacuum at 5 volts. The scan tool can only read a max pressure of 6.0 inches of H2O (0 Volts), however the EVAP service station can pressurize the system to much higher pressures. The scan tool value should be within 0.5 in. H2O of the specified value.