P0442

DTC P0442

SYSTEM DESCRIPTION
This diagnostic tests the evaporative emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met.

Heat from the exhaust system is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned OFF, a change in the fuel tank vapor temperature occurs. With the EVAP system sealed, this results in corresponding pressure changes in the fuel tank vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.51 mm (0.020 in) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.

If the control module detects a pressure change less than a calibrated amount, DTC P0442 sets.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0117, P0118, P0125, P0128, P0443, P0446, P0449, P0451, P0452, P0453, P0455, P0458, P0459, P0498, P0499, P0502, P0560, P0562, P0563 are not set.
- The diagnostic runs once with a 10 hour minimum between tests after a fail.
- DTC P0455 must run and pass.
- The start up intake air temperature (IAT) less than 10°C (50°F).
- The start up engine coolant temperature (ECT) is less than 40°C (104°F).
- The start up IAT and ECT are within 8°C (15°F).
- The barometric pressure (BARO) is more than 68 kPa.
- The ambient air temperature is between 2-40°C (36-104°F).
- The engine run time minimum is 10 minutes.
- The odometer displays more than 10 miles.
- The vehicle has traveled more than 20 km (12.5 miles) this trip.
- The ECT is more than 70°C (158°F).
- The fuel level is between 15-85 percent.
- The battery voltage is more than 11 volts
- The ignition is OFF.
- The fuel level change with the ignition OFF is less than 10 percent.

CONDITIONS FOR SETTING THE DTC
The control module detects a pressure change that is less than a calibrated amount.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- If DTC P0442, P0446, P0445 is set, EVAP special functions on the scan tool will not be allowed. Clear DTCs before performing these tests.
- The ECM uses the FTP sensor to detect the pressure of fuel vapor in the fuel tank during all parts of the EVAP diagnostic system test. Ensure the FTP sensor is not skewed by verifying FTP SENSOR on the scan tool is between 2.35-2.85 volts with the ignition ON and the engine OFF, with the fuel cap removed.
- Possible causes of a small EVAP leak:
- The fuel cap is leaking.
- The EVAP canister vent solenoid valve stuck open.
- The EVAP service port valve is leaking.
- The EVAP line/hose connections are disconnected/leaking.
- The fuel sender O-ring is leaking.
- The FTP sensor seal is leaking.
- To help locate intermittent leaks, use the J 41750 OBD II/Enhanced Emissions Testing Equipment (Cart only) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT.
- To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT.
- Review the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.
- For intermittent conditions refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-4:

Steps 5-6:

The numbers below refer to the step numbers on the diagnostic table.
3. Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
5. This step verifies that repairs are complete and that no other condition is present.