P0440

DTC P0440 EVAP System




Circuit Description
The evaporative system includes the following components:
- Fuel tank
- EVAP canister duty solenoid valve
- Fuel tank pressure sensor
- Fuel pipes and hoses
- Vapor lines
- Fuel cap
- Evaporative emissions canister
- Purge lines
- EVAP canister cut valve (purge solenoid)

The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The powertrain Control module (PCM) monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP canister purge solenoid and the EVAP canister vent solenoid are turned "ON," allowing engine vacuum to draw a small vacuum on the entire evaporative emissions system. If a sufficient vacuum level cannot be achieved, a large leak or a faulty EVAP canister purge solenoid is indicated. This can be caused by the following conditions:
- Disconnected or faulty fuel tank pressure sensor
- Missing or faulty fuel cap
- Disconnected, damaged, pinched, or blocked EVAP purge line
- Disconnected or damaged EVAP vent hose
- Disconnected, damaged, pinched, or blocked fuel tank vapor line
- Disconnected or faulty EVAP canister cut valve
- Disconnected or faulty EVAP canister duty solenoid valve
- Open ignition feed circuit to the EVAP canister vent solenoid or the EVAP canister cut valve
- Damaged EVAP canister
- Leaking fuel sender assembly O-ring
- Leaking fuel tank or fuel filler neck

Any of the above conditions can set DTC P0440.

Conditions for Setting the DTC
- No TP sensor, AT sensor, or MAP sensor DTCs set.
- Start-up engine coolant temperature is less than 32 °C (90 °F).
- Start-up engine coolant temperature is not more than 7 °C (13 °F) greater than start-up intake air temperature.
- Start-up intake air temperature is greater than 4 °C (39 °F).
- Start-up intake air temperature is not more than 2 °C (4 °F) greater than start-up engine coolant temperature.
- Vehicle speed is less than 5 mph (8 kph).
- Throttle position is greater than 3%.
- Minimal fuel slosh.
- BARO is greater than 70 kPa.
- The EVAP system is unable to achieve or maintain vacuum during the diagnostic test.
- Above conditions are present for 60 to 180 seconds.

Action Taken When the DTC Sets
- The PCM will illuminate the MIL during the second key cycle in which the DTC sets.
- The PCM will store conditions which were present when the DTC set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL "OFF" when the diagnostic has been run and the fault condition is no longer present.
- A history DTC P0440 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- DTC P0440 can be cleared by using the Tech 2 "Clear Info" function or by disconnecting the PCM battery feed.

Diagnostic Aids
Check for the following conditions:
- 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 vent solenoid, EVAP canister purge solenoid and the fuel tank pressure sensor for an intermittent open or short circuit.
- Kinked, pinched, or plugged vacuum source, EVAP purge, or fuel tank vapor line-Verify that the lines are not restricted.

Reviewing the Failure 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.

Steps 1 - 3:

Steps 4 - 6:

Steps 7 - 11:

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart:
2. If an EVAP canister vent solenoid or an EVAP canister purge 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 P0440.
3. Checks the fuel tank pressure sensor at ambient pressure.
4. Determines whether or not the EVAP system can be sealed sufficiently to be pressurized. If not, the large leak must be located and corrected before continuing with diagnosis.
5. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes.
8. Checks for a blocked EVAP canister purge solenoid. The PCM commands the EVAP canister purge solenoid "OFF" (open) and the vent solenoid "ON" (closed) with the Tech 2 "System Perf." EVAP output Control function activated. Any pressure in the system should be released through the EVAP canister purge solenoid within a few seconds when "System Perf." is activated.
9. Ensures that sufficient source vacuum is present at the EVAP canister purge solenoid.