What does it mean?
P1440 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Fuel Tank Pressure Control System Function Problem (low input) .
Symptoms
- MIL on with the EVAP monitor incomplete
- Rough idle or stalling shortly after refuelling if the purge valve is stuck open
- Fuel vapour smell around the vehicle
- A hiss when the filler cap is opened is absent, or unusually strong
- Slight increase in fuel consumption in some cases
Likely causes
- Fuel tank pressure sensor reading low because of a shorted signal wire or a failed element
- Purge valve stuck open, holding constant vacuum on the tank
- Vent valve stuck open, so the system can never build or hold pressure
- Cracked or disconnected vapour hose between the tank, canister and purge valve
- Loose, damaged or incorrect fuel filler cap sealing poorly
- Blocked or kinked hose to the pressure sensor port
- Corroded connector or damaged wiring in the underbody EVAP harness
How to fix it
- Read the fuel tank pressure value in live data with the engine off; it should be close to atmospheric
- Check the filler cap seal and confirm the correct cap type is fitted
- Inspect all vapour hoses between the tank, canister, purge and vent valves for cracks, kinks and disconnection
- Command the purge valve closed and confirm it holds vacuum without leaking
- Verify the vent valve closes and seals when commanded, since a stuck open vent prevents pressure build up
- Test the pressure sensor reference, ground and signal wiring back to the PCM
- Replace the leaking valve or faulty sensor, then run the EVAP monitor to confirm the system holds pressure