P0443

Evaporation Emission (EVAP) System Incorrect Purge Flow:

Evaporation Emission (EVAP) System Incorrect Purge Flow (continued):

Evaporative Emission (EVAP) System Incorrect Purge Flow (continued):

Evaporation Emission (EVAP) System Incorrect Purge Flow:

Circuit Description

An evaporative emission control system is used to prevent emission of fuel vapor. The vapor generated in the fuel tank while driving or the engine is at a stop, passes through a tank pressure control valve and enters the Evaporative Emissions (EVAP) System canister where the charcoal absorbs and stores fuel vapors.


Conditions for Running the DTC

^ Engine coolant temperature between 70°C (158°F) and 110°C (230°F).

^ Intake air temperature between -10°C (14°F) and 5O°C (122°F).

^ Barometric pressure greater than 75 kPa.

^ Fuel tank level is between 25 and 75%

^ At idle in closed loop.


Conditions for Setting the DTC

^ Engine speed change between purge "OFF" and "ON" (duty greater than 50%) during Idle mode:

^ Conditions present for 20 seconds.


Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

^ The MIL will turn "OFF" after three consecutively passing cycles without a fault present.

^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.

^ DTC(s) can be cleared by using a scan tool or by disconnecting the PCM battery feed.


Diagnostic Aids

Check for the following conditions:

^ Missing or damaged O-rings at EVAP canister fuel vapor and purge line liftings.

^ Cracked or punctured EVAP canister.

^ Damaged or disconnected source vacuum line. EVAP purge line. Vent hose or fuel tank vapor line.

^ 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 canister purge valve for an intermittent open or short circuitry.

^ Pinched or plugged vacuum source. EVAP purge line. or fuel tank vapor line. Verify that the lines are not restricted.

If DTC P0443 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.
If any wiring repairs need to be made, Refer to Repair Procedures in Diagrams.


Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.


1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. Determine if the fault is present. Review Freeze Frame data to determine when the DTC set. Always record this information.

3. Indicates whether the malfunction is in the control circuitry or in the EVAP canister.

7. An EVAP canister purge valve test. Output Control can be found on the scan tool under Misc. Test.

10. An EVAP canister test.