P0442

Diagnostic Chart 1 Of 2:

Diagnostic Chart 2 Of 2:

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 set.

The following conditions will set DTC P0442:
^ A loose or malfunctioning fuel fill cap
^ A damaged EVAP purge or vapor pipes
^ A damaged EVAP fresh air vent hose
^ A malfunctioning EVAP vent valve
^ A damaged EVAP Canister.
^ A leaking fuel tank, fuel sender assembly O-ring or pressure relief valve
^ A leaking fuel filler neck or seal

CONDITIONS FOR RUNNING THE DTC
^ DTC P0443 or P0449 is not active.
^ There are no throttle position (TP), intake air temperature (IAT), fuel tank pressure (FTP), engine coolant temperature (ECT) or manifold absolute pressure (MAP) sensor DTCs set.
^ The system voltage is between 10-18 volts.
^ The DTC P0440 diagnostic test has passed.
^ The start-up ECT is not more than 4°-30°C (39°-86°F).
^ The start-up ECT is not more than 8°C (14°F) above the IAT start-up temperature.
^ The start-up IAT not more than 4°-30°C (39°-86°F).
^ The start-up IAT is not more than 3°C (7°F) above the ECT start-up temperature.
^ The fuel tank level is between 15-85 percent for a 0.040-0.060 leak.
^ The fuel tank level is between 30-85 percent for a 0.020 leak.
^ The BARO is more than 75kPa (10.87 psi).
^ The IAT is less than 30°C (86°F)
^ The VSS below 128.75 km/h (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/Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the MIL OFF during the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC clear when the PCM turns off the MIL.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
Check for the following conditions:
^ A cracked or punctured EVAP canister
^ A damaged source vacuum line, EVAP purge line, EVAP vent hose, or fuel tank vapor line
^ A defective or incorrect fuel fill cap
^ Charcoal release from the EVAP canister

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.

TEST DESCRIPTION
Numbers below refer to the step numbers on the Diagnostic Table:
1. The powertrain On Board Diagnostic (OBD) System Check prompts you to complete some of the basic checks 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.