P0442
DTC P0442
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0442
- Evaporative Emissions (EVAP) System Small Leak Detected
Circuit/System Description
The engine off natural vacuum test is the small leak detection diagnostic for the evaporative emission system. This diagnostic tests the evaporative emission 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 evaporative emission 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 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
Important: The following conditions must be met prior to ignition OFF.
* DTCs P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0120, P0125, P0128, P0443, P0446, P0449, P0452, P0453, P0455, P0461, P0462, P0463, P0496, P1516, P2101, P2120, P2125, P2138, P2610 are not set.
* The diagnostic runs once after a cold start drive cycle.
* The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
* The start-up engine coolant temperature (ECT) is less than 30°C (86°F).
* The start-up IAT and ECT are within 8°C (15°F).
* The barometric pressure (BARO) is more than 74 kPa.
* The ambient air temperature is between 2-32°C (36-90°F).
* The engine run time minimum is 10 minutes.
* The vehicle has traveled more than 8 kilometers (5 miles) this trip.
* The ECT is more than 70°C (158°F).
* The fuel level is between 10-90 percent.
* The ignition is OFF.
* A refueling event is not detected.
* DTC P0442 runs once per drive cycle when the above conditions are met.
* 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. The time since the last completed engine off natural vacuum test must be at least 17 hours.
Conditions for Setting the DTC
* The ECM detects a pressure change that is less than a calibrated amount.
* The ECM must complete several engine OFF natural vacuum (EONV) tests before the diagnostic can turn the malfunction indicator lamp (MIL) ON or OFF.
Action Taken When the DTC Sets
DTC P0442 is a Type A DTC.
Conditions for Clearing the MIL/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 adapter temporarily leave the vent open until smoke is observed then close the system and continue testing.
* To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT .
* 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
Schematic Reference
Evaporative Emissions Hose Routing Diagram (Evaporative Emissions Hose Routing Diagram)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Description and Operation
Evaporative Emission Control System Description (Evaporative Emission Control System Description)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
* J 41413-VLV EVAP Port Vent Fitting Tool
* CH-48096 EVAP Service Access Port Tool
* J 41413-200 Evaporative Emission System Tester (EEST)
* GE-41415-50 Fuel Tank Cap Adapter
* J 41413-SPT High Intensity White Light
Circuit/System Testing
Important:
* Refer to the J 41413-200 operation manual for detailed instructions in Evaporative Emission System Diagnosis (Evaporative Emission System Diagnosis).
* Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
* Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. The system flow will be less with higher temperatures.
1. Connect the J 41413-200 to the vehicle at the EVAP service port. For vehicles without a service port, disconnect the purge tube at the quick connector on the EVAP canister side of the purge solenoid valve and install the CH-48096 .
2. Using the scan tool, close the EVAP canister vent valve to seal the EVAP system.
3. Use the flow meter on the J 41413-200 , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.
• If a leak is detected, use the J 41413-200 to apply smoke to the EVAP system at the service port or the purge tube until the leak is located using the J 41413-SPT .
Repair Verification
1. Seal the EVAP system and use the flow meter on the J 41413-200 , calibrated to 0.51 mm (0.020 in) to determine that there is no leak in the EVAP system.
2. Clear DTCs.