P0440: Evaporative Emission Control System Malfunction

The P0440 error code signifies an "Evaporative Emission Control System Malfunction." This code is triggered when the engine control module detects an issue within the evaporative emission control (EVAP) system. The EVAP system is designed to prevent fuel vapors from escaping into the atmosphere by capturing them and recycling them back into the engine to be burned. Several conditions could trigger this code — a loose gas cap, a leak in the fuel tank or vapor lines, or a malfunctioning component within the EVAP system.

Importance of addressing P0440

Addressing the P0440 code is important because it can lead to increased emissions and could cause the car to fail an emissions test. The EVAP system helps limit environmental pollution, so a malfunction can contribute to environmental harm and may affect overall fuel efficiency.

Can I safely drive my car with this error code?

Yes, driving with the P0440 code is generally safe and does not pose an immediate risk to vehicle performance. However, an EVAP malfunction can lead to environmental pollution, reduce fuel efficiency over time, and prevent the vehicle from passing emissions tests. It is advisable to address this code as soon as possible.

Common symptoms of P0440

• Check engine light is illuminated
• Fuel smell around the vehicle
• Slight decrease in fuel efficiency
• Failed emissions test

Diagnosing P0440

To diagnose the P0440 code, a technician typically follows these steps:

1. OBD-II scanner: Confirm the P0440 code with an OBD-II scanner and check for any other related codes.
2. Visual inspection: Inspect the gas cap for looseness or damage and check the EVAP system hoses and connections for any visible leaks or signs of wear.
3. Smoke test: Introduce smoke into the EVAP system to locate leaks in hoses, connections, or the fuel tank itself.
4. Check solenoids and valves: Use a multimeter to test EVAP solenoids and valves to ensure they are working correctly and not causing the leak.

Repairing P0440

Repairs for the P0440 code vary based on the cause but may include:

1. Tighten or replace gas cap: If the gas cap is loose or damaged, tightening or replacing it may resolve the code.
2. Repair or replace EVAP hoses: Damaged or leaking EVAP hoses should be repaired or replaced to restore proper vapor containment.
3. Replace faulty components: Faulty EVAP components such as the purge valve or vent solenoid should be replaced if they are not functioning correctly.
4. Clear the code and test: After repairs, the P0440 code should be cleared using an OBD-II scanner, followed by a test drive to ensure the issue is resolved.

Related reading

Follow the link below to reach our diagnostic check engine trouble codes catalog:
On-board diagnostics (OBD-II) trouble code directory