P0446

Evaporative Emission Control System Circuit:

Circuit Description
A restricted or blocked Evaporative Vapor (EVAP) canister vent path is detected by drawing vacuum into the EVAP system, turning "OFF" the EVAP vent solenoid and the EVAP purge solenoid (EVAP vent solenoid "Open," EVAP purge PWM "0%") and monitoring the fuel tank vacuum sensor input. With the EVAP vent solenoid open, any vacuum in the system should decrease quickly unless the vent path is blocked.

Conditions for Setting the DTC
- The BARO is greater than 70 kPa
- The intake air temperature is between 4°C and 30°C at engine start up
- The engine coolant temperature is between 4°C and 30°C at engine start up
- The Engine Coolant Temperature (ECT) sensor and Intake Air Temperature (IAT) sensor are within 4°C at engine start up
- The Throttle Position (TP) sensor is between 9 and 35%
- The engine run time is greater than 120 sec.
- Fuel tank level is between 15% and 85%
- One or more of the following DTCs are not set P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134 and P1133.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn "OFF" after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- DTCs can be cleared by using a scan tool.

Diagnostic Aids
Check for the following conditions:
- Poor connection at PCM Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness. Inspect the wiring harness to the EVAP vent solenoid and the fuel tank pressure sensor for an intermittent open or short circuit.
- Kinked, pinched or plugged vent hose. Verify that the vent hose between the canister and the EVAP vent solenoid is not restricted.

NOTE: Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

DTC P0446 - Evaporative Emission Control System Vent Control (1 Of 2):

DTC P0446 - Evaporative Emission Control System Vent Control (2 Of 2):

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
1. The OBD System 0heck prompts the Technician to complete some basic checks and store the Freeze Frame Data and the Failure records on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. This information on the scan tool can be referred to later.
2. Whenever a vent solenoid electrical fault is present, the purge system will not operate correctly. Repairing the electrical fault will very likely correct the condition that set DTC P0446.
6. Checks the fuel tank vacuum sensor at ambient pressure.
7. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
9. Checks for a blocked EVAP canister.