P0443

Diagnostic Chart:

Wiring Diagram:

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 EVAP 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 50°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.

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for any of the following conditions:

^ A cracked or punctured EVAP canister.

^ A damaged or disconnected source vacuum line, EVAP purge line, vent hose or fuel tank vapor line.

^ A plugged, restricted, leaking or damaged EVAP Canister Surge Tank.

^ A poor connection at the PCM. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ A damaged wiring harness. Inspect the wiring harness to the EVAP canister purge valve for an intermittent open or short circuitry.

If a 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 Electrical Diagrams.

Test Description

The numbers below refer to the step numbers in 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.

4. This step checks the components that supply manifold vacuum to the EVAP canister purge valve. A plugged or leaking EVAP canister surge tank could prevent vacuum from reaching the EVAP canister purge valve.

6. An EVAP canister purge valve test. Duty cycle control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (178°F) and there is no RPM input. Output controls can be found on the Tech 2 scan tool under Special Functions.

8. An EVAP canister purge valve control circuit test. The EVAP canister purge valve duty cycle control is disabled by the PCM until the engine has reached a normal operating temperature of at least 80°C (176°F) and there is no RPM input. Output controls can be found on the Tech 2 scan tool under Special Functions.

9. This step checks the EVAP canister.