the ECM.
5. If all circuits test normal, replace the appropriate solenoid valve.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Evaporative Emission Canister Purge Solenoid Valve Replacement (See: Powertrain Management/Emission Control Systems/Evaporative
Emissions System/Canister Purge Solenoid/Service and Repair)
* Evaporative Emission Canister Vent Solenoid Valve Replacement (1500 Series) (See: Powertrain Management/Emission Control
Systems/Evaporative Emissions System/Evaporative Emission Control Canister/Canister Vent Valve/Service and Repair/Evaporative
Emission Canister Vent Solenoid Valve Replacement (1500 Series))Evaporative Emission Canister Vent Solenoid Valve Replacement (2500
Series) (See: Powertrain Management/Emission Control Systems/Evaporative Emissions System/Evaporative Emission Control
Canister/Canister Vent Valve/Service and Repair/Evaporative Emission Canister Vent Solenoid Valve Replacement (2500 Series))
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P0446
DTC P0446
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0446
- Evaporative Emissions (EVAP) Vent System Performance
Typical Scan Tool Data
Circuit/System Description
This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path that would cause excess amounts of vacuum to
be developed in the EVAP system. With the purge valve open and the canister vent valve open, if the EVAP system vacuum goes above a
calibrated threshold, the test will fail.
Conditions for Running the DTC
* DTCs P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0442, P0443, P0449, P0451,
P0452, P0453, P0454, P0464, P0496, P0608, P0609, P0641, P0651, P1516, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128,
P2135, P2138 are not set.
* The ignition voltage is between 11-18 volts.
* The barometric pressure (BARO) is more than 74 kPa.
* The fuel level is between 15-85 percent.
* The engine coolant temperature (ECT) is less than 35锟斤拷C (95锟斤拷F).
* The intake air temperature (IAT) is between 4-30锟斤拷C (39-86锟斤拷F).
* DTC P0446 runs once per cold start when the above conditions are met.
Conditions for Setting the DTC
* The fuel tank vacuum is greater than -12 inches H2O vacuum for 5 seconds.
OR
* The FTP is less than -2.5 inches H2O or more than +5 inches for 60 seconds after a cold start.
Action Taken When the DTC Sets
