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 (FTP) 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

* DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0111, P0112, P0113, P0114, P0116, P0117, P0118, P0119, P0128, P0121, P0122, P0123, P0222, P0223, P0443, P0449, P0452, P0453, P0454, P0502, P0503, P0606, P0697, P06A3, P0722, P0723, P16F3, P2101, P2122, P2123, P2127, P2128, P2135 and P2138 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 fuel level is between 10-90%.

* This DTC runs once per cold start when the above conditions are met.

Conditions for Setting the DTC

The FTP sensor is less than -2.5 inches H2O vacuum or greater than +5 inches H2O vacuum for 60 s.

OR

The FTP sensor is greater than 12 inches H2O vacuum for 5 s before the purge volume is greater than 10 L (2.6 gal). After setting the DTC for the first time, 2 liters (0.5 gal) of fuel must be consumed before setting the DTC for the second time.

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 [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

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 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 repair.

* Evaporative Emission Canister Purge Solenoid Valve Replacement Service and Repair

* Evaporative Emission Canister Replacement (Steel Tank) Service and Repair