P0442

EVAP System:

EVAP System Small Leak Detected:

P0442- EVAP SYSTEM SMALL LEAK DETECTED
The evaporative emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The EVAP system consists of the EVAP canister, fuel tank pressure (FTP) sensor, EVAP lines and hoses, EVAP purge solenoid (normally closed), EVAP service port, EVAP vent solenoid ,normally open) and fuel tank. The ECM monitors the EVAP system for circuit faults in the EVAP purge solenoid, EVAP vent solenoid and FTP sensor circuit. The ECM also monitors the EVAP system for leaks (between EVAP vent and EVAP purge solenoid). When certain conditions have been met, the ECM will perform an EVAP diagnostic test at idle with no vehicle speed. which will require a five consecutive phase (A, B, C, D and F) test. DTC P0442 will set if vacuum decays too quickly during Phase E of the EVAP diagnostic system test indicating a small EVAP system leak.

DTC PARAMETERS
DTC P0442 will set if the vacuum decay is greater than 0.35 fuel tank pressure sensor volts [change from -6.00 mmHg (-3.21 in H2O) to higher than -3.00 mmHg (-1.61 in H2O)] over a 10.5 second period during phase F of the EVAP diagnostic system test indicating a small EVAP leak when;
^ Condition exists for the entire phase E of 10.5 seconds
^ EVAP purge solenoid is commanded Off
^ EVAP vent solenoid is commanded On
^ Engine is at idle
^ Vehicle speed 0 mph
^ Engine load is less than 35%
^ MAP is less than 40 kPa
^ Battery voltage is greater than 11.0 volts
^ Start-up ECT is between 8°C and 75°C (460 and 167°F)
^ IAT is between 8°C and 75°C (460 and 122°F)
^ Long term fuel trim cells learned (if not learned, engine must run longer than 16 minutes and 45)
^ Fuel level is between 6 and 48L (1.6 and 12.7 gallons)
^ No ECT, EVAP purge solenoid, EVAP vent solenoid, fuel tank pressure, idle speed HO2S, throttle actuator, TP sensor or vehicle speed DTCs have been set.

DTC P0442 diagnostic runs once during phase F of the EVAP diagnostic system test once per ignition cycle. If an EVAP diagnostic test is aborted due to changing enable criteria, the ECM will attempt to rerun the entire EVAP diagnostic system test up to three times per ignition cycle.

P0442 is a type B DTC

DIAGNOSTIC AIDS

IMPORTANT: If any EVAP system DTC is set, EVAP special functions on Scan tool will not be allowed. Clear DTCs before performing these tests.

IMPORTANT: The ECM uses the fuel tank pressure sensor to detect the vapor in the fuel tank during all parts of the EVAP diagnostic system test. Make sure the fuel tank pressure sensor is not skewed by verifying FUEL TANK PRESS. SENSOR on Scan tool is between 2.35 and 2.85 volts with ignition On and engine Off and fuel cap removed.

Use the EVAP System Tester to locate the small leak. Follow operating instructions in the "EVAP System Description".

Refer to "EVAP System Description" for a complete EVAP diagnostic test description.

Possible cause of a small EVAP leak:
^ Fuel cap leaking
^ EVAP vent solenoid valve not fully seating
^ EVAP service port valve leaking
^ EVAP line/hose connections leaking
^ Fuel sender O-ring leaking
^ Fuel tank pressure sensor seal leaking

USE THE EVAP SYSTEM PICTURE WHICH WILL POINT TO POSSIBLE LEAK AREAS.