P0446

DTC P0446 (LUW)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptor
DTC P0446
- Evaporative Emission (EVAP) Vent System Performance

Circuit/System Description

A restricted or blocked evaporative emission (EVAP) vent path is detected by the engine control module (ECM) commanding the purge valve ON (open) and the vent valve ON (closed) allowing a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the purge valve OFF (closed) and the vent valve OFF (open) while monitoring the fuel tank pressure sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 kPa (0 PSI) in a calibrated time, DTC P0446 will set.

Conditions for Running the DTC

Note: The following conditions must be met prior to ignition OFF.

* DTCs P0106, P0107, P0108, P0112, P0113, P0114, P0116, P0117, P0118, P0122, P0123, P0222, P0223, P0443, P0449, P0451, P0452, P0453, P0454, and P2135 are not set.
* The ignition voltage is between 11-32 V.
* The barometric pressure (BARO) is greater than 70 kPa (10.15 PSI).
* The start up Engine Coolant Temperature (ECT) is less than 35°C (95°F).
* The start up Intake Air Temperature (IAT) is between 4-30°C (40-86°F).
* The purge enable time is less than predetermined value based on startup ECT.
* The fuel level is between 10-90%.
* The engine run time is between 1-360 s plus purge enable time.
* The DTC run once an ignition cycle when the above conditions are met.

Conditions for Setting the DTC

* The fuel tank pressure is greater than 27 kPa (3.9 PSI) at cold engine startup.
* The above condition is present for at least 5 s.

Action Taken When the DTC Sets

DTC P0446 is a Type B DTC.

Conditions for Clearing the DTC

DTC P0446 is a Type B DTC.

Diagnostic Aids

An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill condition and a stalling condition.

Reference Information
Schematic Reference

Engine Controls Schematics (LUW) [1][2]Electrical Diagrams
Connector End View Reference

Component Connector End Views Sunshade - Left (D6I)
Description and Operation

Evaporative Emission Control System Description Description and Operation
Electrical Information Reference

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P0443, P0449, P0452, or P0453 are not set.

• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition OFF, remove the fuel tank filler cap.
3. Ignition ON, observe the scan tool Fuel Tank Pressure sensor voltage parameter. The B150 Fuel Tank Pressure Sensor voltage parameter should be within 1.3-1.7 V.

• If greater than the specified range, refer to DTC P0452 or P0453 (LUW) P0452.

4. Install the fuel tank filler cap.
5. Engine idling at operating temperature for 5 min, command the EVAP Canister Purge Solenoid Valve to 50%. The Fuel Tank Pressure Sensor voltage parameter should not increase to greater than 2.5 V.

• If greater than the specified value, inspect for a blockage or restrictions in the EVAP system components listed below and repair as necessary:

* EVAP vent system hoses
* EVAP canister
* EVAP vent valve

6. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Evaporative Emission Canister Purge Solenoid Valve Replacement Service and Repair
* Evaporative Emission Canister Replacement Service and Repair