P0440

Diagnostic Chart:

The evaporative emission system is tested with on-board diagnostics by applying pressure (vacuum) to the system and monitoring pressure decay. The PCM monitors the vacuum level at the fuel tank pressure sensor. At the appropriate time, the vent solenoid is commanded closed (normally open valve) and the canister purge solenoid is commanded to a fixed duty cycle, allowing the engine to draw a vacuum on the entire evaporative emission system. After a calibrated vacuum level is achieved, the canister purge solenoid is turned off, sealing the system. If a sufficient vacuum pressure level cannot be achieved, a large leak fault is detected. Following is a list of possible conditions that result in large leak detection:
^ Missing, improperly installed (loose) or faulty fuel cap.
^ Disconnected or faulty fuel tank pressure sensor, EVAP purge solenoid or EVAP vent solenoid.
^ Disconnected or damaged EVAP vent hose.
^ Disconnected, damaged, pinched or blocked EVAP purge line.
^ Disconnected, damaged, pinched or blocked fuel tank vapor lines.
^ Damaged or leaking EVAP canister.
^ Leaking fuel sender assembly or O-ring.
^ Leaking fuel tank or filler neck.

DTC PARAMETERS
^ Baro is greater than 75 kPa.
^ Both ECT and IAT are between 4°C (39°F) and 30°C (86°F) at engine start up.
^ ECT is not more than 8°C (14°F) greater than IAT at startup.
^ IAT is not more than 1.5°C (30°F) greater than ECT at startup.
^ Throttle angle is between 7% and 35%.
^ EVAP purge solenoid is enabled.
^ Fuel tank level is between 15% and 85%.
^ Vehicle speed is less than 113 km/h (70 mph).
^ DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0132, P0133, P0134, P0452, P0453, P0502, P0503, P0601, P0602, P1133 and P1621 are not set.
^ Fuel tank pressure is greater than 1.0 volts for 400 seconds.

DIAGNOSTIC AIDS
^ If DTC P0460 is also set the P0440 cannot be considered valid until you repair and clear DTC P0460.
^ Review and record freeze frame/failure record data.
^ A warm test is performed by the diagnostic if the cold test fails. The warm test can only Pass the diagnostic. The purpose of this additional test is to allow the fuel cap to be reinstalled if left off, allowing the MIL to be extinguished.

IMPORTANT: Very large leaks, such as fuel cap off or a hose disconnected, are difficult to detect using the ultrasonic leak detector. Before using the leak detector, perform a thorough visual inspection of all hoses.

^ Use the EVAP Pressure/Purge Diagnostic Cart and the Ultrasound Leak Detector to locate leak.