Possible causes

– Incorrect fuel tank vacuum relief valve
– Incorrect fuel filler cap used
– Fuel filler cap remains open or fails to close
– Foreign matter caught in fuel filler cap
– Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve
– Foreign matter caught in EVAP canister vent control valve
– EVAP canister or fuel tank leaks
– EVAP purge line (pipe and rubber tube) leaks
– EVAP purge line rubber tube bent
– Blocked or bent rubber tube to EVAP control system pressure sensor
– Loose or disconnected rubber tube
– EVAP canister vent control valve and the circuit
– O-ring of EVAP canister vent control valve is missing or damaged
– EVAP canister is saturated with water
– EVAP control system pressure sensor
– Absolute pressure sensor

Tech notes

The most common cause for the P1440 code is a loose or missing fuel filler cap. Resecure or install the cap and reset the engine light. In some cases the light will turn off by itself after a few days driving the vehicle. if the problem persist replaced the gas cap.

When is the code detected?

When EVAP control system has a leak, EVAP control system does not operate properly

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)
– Possible gas smell

P1440 NISSAN Description

This diagnosis detects leaks in the Evaporative Emission (EVAP) purge line using of vapor pressure in the fuel tank. The EVAP canister vent control valve is closed to shut the EVAP purge line. The vacuum cut valve bypass valve will then be opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP control system pressure sensor can now monitor the pressure inside the fuel tank. If pressure increases, the Engine Control Module (ECM) will check for leaks in the line between the vacuum cut valve and EVAP canister purge volume control solenoid valve.