Chevrolet Trax: 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 (EVAP) system. This diagnostic tests the 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 vehicle is turned OFF and the EVAP system is sealed a change in the fuel tank vapor temperature occurs which results in a corresponding pressure change in the fuel tank vapor space. This change is monitored by the ECM using the fuel tank pressure (FTP) 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 P010C, P010D, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0125, P0128, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P0461, P0462, P0463, P0464, P0496, P0502, P0503, P0722, P0723, P2227, P2228, P2229, P2230, P2610. are not set.
• The barometric pressure (BARO) is greater than 70 kPa.
• The engine coolant sensor (ECT) is greater than 63ºC (145ºF)
• No fuel filling during the EONV test period.
• The fuel level is between 10-90%.
• The start-up engine coolant temperature (ECT) and the start-up intake air temperature (IAT) are within 8º C (46ºF).
• The engine run time before shut-off was greater than 10 min.
• The drive distance before engine shut-off was more than 5 km (3 mi).
• The ambient air temperature at the end of the drive cycle is between 0-34ºC (32-93ºF).
• DTC P0442 runs once per drive cycle during the hot soak period after the ignition is turned OFF and may require up to 40 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 h if passed or 10 h if failed.

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 EVAP 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 GE 41413-A , move all EVAP components while observing smoke with the GE 41413-SPT .
• Individual components can be isolated and tested using adapters in the GE 41413-300 .
• When servicing the EVAP system, test pressure must not exceed 13 in H20 (0.5 PSI) as pressure in excess of this could cause system components to perform inaccurately.
• A condition may exist where a leak in the EVAP 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 EVAP system and then observe the FTP parameter for vacuum decay.

Reference Information

Schematic Reference

Engine Controls Schematics (Encore) , Engine Controls Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

• CH 48096 EVAP Service Port Access Tool
• GE 41413-A Evaporative Emissions System Tester (EEST)
• GE 41413-300 EVAP Cap and Plug Kit
• GE 41413-SPT High Intensity White Light

For equivalent regional tools, refer to Special Tools (Diagnostic Tools) .

Circuit/System Testing

NOTE:

• Refer to the GE 41413-A operation manual for detailed instructions in Evaporative Emission Control System Diagnosis
• Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize or produce smoke from a leak.
• Ensure that the underbody temperature of the vehicle and the tester are similar.

1. Disconnect the purge tube at the quick connector on the EVAP canister side of the Q12 Evaporative Emission Canister Purge Solenoid Valve and install the CH 48096 .
2. Connect the GE 41413-A to the CH 48096 .
3. Command the EVAP Purge/Seal function to System Seal with a scan tool to seal the EVAP system.
4. Use the flow meter on the GE 41413-A , calibrated to 0.51 mm (0.020 in) to determine if there is a leak.

• If a leak is detected

1. Use the GE 41413-A to apply smoke to the EVAP system at the purge tube until the leak is located using the GE 41413-SPT

• No leak in the EVAP system

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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