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DTC P0442

DTC P0442

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptor

DTC P0442

Evaporative Emission (EVAP) System Small Leak Detected

Circuit/System Description

The engine off natural vacuum (EONV) test is the small leak detection diagnostic for the evaporative emission system. 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 the fuel tank while the vehicle is operating. When the engine is switched OFF and the EVAP system is closed, a change in the vapour temperature occurs in the fuel tank. This results in a corresponding pressure change in the fuel tank compartment for fuel vapours. This change is monitored by the ECM using the fuel tank pressure sensor input. With a leak in the system, the amount of pressure change will be less than that of a sealed system.

Conditions for Running the DTC


• DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0222, P0223, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0461, P0462, P0463, P0464, P0496, P0502, P0503, P0608, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138 are not set.

• The ignition 1 voltage is between 10-16 V.

• The barometric pressure (BARO) is greater than 74 kPa.

• No fuel filling during the EONV test period.

• The fuel level is between 15-85 percent.

• The start-up engine coolant temperature (ECT) and the start-up intake air temperature (IAT) are between 0-40°C (32-104°F).

• The barometric pressure (BARO) is greater than 74 kPa.

• The engine run time before engine shut-off was greater than 10 min.

• The drive distance before engine shut-off was more than 5 kilometers (3.1 miles).

• The ignition is OFF.

• The ambient air temperature at the end of the drive cycle is between 0-32°C (32-93°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 min to complete. The controller will not make more than 2 test attempts per day. The time since the last completed EONV test must be at least 17 hours.


Conditions for Setting the DTC


• The ECM detects a leak in the EVAP system that is greater than a calibrated amount.

• The ECM must complete several EONV tests before the diagnostic can turn the MIL ON or OFF.


Action Taken When the DTC Sets

DTC P0442 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0442 is a Type A DTC.

Diagnostic Aids


• The evaporative emission system can be filled with smoke more quickly and completely by opening the system opposite the end where the smoke is injected. When injecting smoke at the service port tool temporarily leave the EVAP vent solenoid valve open until smoke is observed then close the system and continue testing.

• To help locate intermittent leaks using the EN 41413-A EEST, move all evaporative emission components while observing smoke with the EN 41413-SPT White Light.

• Individual components can be isolated and tested using adapters in the EN 41413-300 Kit.

• A condition may exist where a leak in the evaporative emission system only exists under a vacuum condition. This type of leak may be detected by using the scan tool Purge/Seal function to create a vacuum in the evaporative emission system and then observe the fuel tank pressure parameter for vacuum decay.


Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Description and Operation

Evaporative Emission Control System Description

Scan Tool Reference

Control Module References for scan tool information

Special Tools


• CH 48096 EVAP Service Port Access Tool

• EN 41413 A Evaporative Emissions System Tester (EEST)

• EN 41413 300 EVAP Cap and Plug Kit

• EN 41413 SPT High Intensity White Light


For equivalent regional tools, refer to Special Tools .

Circuit/System Testing

Note
• Refer to the EN 41413-A EEST operation manual for detailed instructions in Evaporative Emission Control System Description .

• Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.

• Ensure that the underbody temperature of the vehicle and the tester are similar.



1. Disconnect the purge tube at the quick connector on the evaporative emission canister side of the Q12 evaporative emission canister purge solenoid valve and install the CH 48096 Port Tool.

2. Connect the EN 41413-A EEST to the CH 48096 Port Tool.

3. Using a scan tool close the evaporative emission canister vent solenoid valve to seal the evaporative emission system.

4. Use the flow meter on the EN 41413-A EEST , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the evaporative emission system.

5. If a leak is detected, use the EN 41413-A EEST to apply smoke to the evaporative emission system at the purge tube until the leak is located using the EN 41413-SPT White Light.


Repair Verification


1. Seal the EVAP system and use the flow meter on the EN 41413-A EEST , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.

2. Clear DTCs.