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 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, which 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 (0.02 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected

Conditions for Running the DTC

* DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0461, P0462, P0463, P0464, P0496, P0222, P0223, P0608, P2101, P2119, P2120, P2122, PP2123, P2125, P2127, P2128, P2135, P2138 are not set.
* No fuel filling during the engine OFF natural vacuum (EONV) test period.
* The fuel level is between 15-85 percent.
* The barometric pressure (BARO) is more than 74 kPa.
* The engine run time before engine shut-off was greater than 10 minutes.
* The drive distance before engine shut-off was more than 5 kilometers (3.1 miles).
* The ignition is OFF.
* The ambient air temperature (AAT) at the end of the drive cycle is between 2-32°C (36-89°F).
* DTC P0442 runs once per drive cycle during the hot soak period after the ignition is turned OFF, and may require up to 45 minutes to complete. The controller will not make more than 2 test attempts per day, and the time since the last complete EONV test must be at least 17 hours.

Conditions for Setting the DTC

* The control module detects a leak in the EVAP system that is greater than a calibrated amount.
* Several EONV tests must complete before the diagnostic can report the results.

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

* To help locate intermittent leaks, use the J 41413-200 Evaporative Emission System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light.
* A condition may exist where a leak in the EVAP system only exists under a vacuum condition. This condition may be detected by using a scan tool PURGE/SEAL function to seal the EVAP system and create a vacuum. Then observe the FTP parameter for vacuum decay.
* To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT.
* For intermittent conditions, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

Test Description

Step 1 - Step 3:

Step 4 - Step 7:

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.