DTC P0440 (EVAP): EVAP Emission Control System
- Connect scan tool. Retrieve DTC(s). If any other DTC(s) are set, diagnose those codes first. If DTC P0440 is only code set, turn ignition off. Check fuel filler cap for tightness. Check for damaged or broken seal in fuel filler cap. Replace fuel filler cap as necessary. If fuel filler cap is okay, go to next step.NOTE: Impreza 2.2L and Legacy models are equipped with a drain valve which may also be referred to as a vent control solenoid. They perform the same function.
- Connect test mode connector (behind left side of dash). Turn ignition on. Listen for clicking sound from vent control solenoid (underneath right rear corner of vehicle). If clicking sound is heard, go to next step.
- Listen for clicking sound from purge control solenoid (under intake runner). If clicking sound is heard, go to next step. If clicking sound is not heard, replace purge control solenoid.
- Listen for clicking sound from pressure control solenoid. On Impreza 2.2L, pressure control solenoid is located underneath right rear corner of vehicle. On all other models, pressure control solenoid is located underneath vehicle, close to right front of fuel tank. If clicking sound is heard, go to next step. If clicking sound is not heard, replace pressure control solenoid.
- Turn ignition off. Check for leaking fuel lines or fuel tank, damage to canister or leaking or plugged evaporative system hoses. Repair or replace as necessary.