Engine control module (ECM/PCM/ECU), if it detects fuel tank vapour leakage (EVAP), or receives an unfavorable signal from the pressure sensor, will generate fault code P0440.
The Evaporative Emissions Control System (EVAP), which is made up of fuel lines and hoses as well as vent valves and other components, prevents fuel vapours escaping into atmosphere. This system is used by your vehicle to collect fuel vapours. Fuel vapours can be stored in a canister of carbon via a system of hoses. A relief valve opens when the engine is running and fuel vapours enter the combustion chamber of the engine and are burned.
Fuel vapours cannot escape into the air when the system is functioning properly. The P0440 code is a result of a significant leak in your system. This leak may go unnoticed, but this is a serious issue that must be addressed immediately.
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What are the symptoms of fault code P0440?
You will not be able to tell if your vehicle is performing better or worse despite a large vapour leak. The engine warning light will illuminate and the ECU will display the fault code P0440.
You may smell petrol inside or around your vehicle if the leak is significant.
Even if there are no performance problems, it is important to have the evaporative emission control system checked.
What causes P0440 fault code?
- If a pressure drop is detected that exceeds the ECU‘s test parameters, the fault code P0440 will be set.
- The P0440 code is set if a pressure drop is detected that exceeds the ECU test parameters.
- The P0440 code will also be triggered if there is a fuel vapour leak in one of the components that make up the fuel vapour system, including the vent valve on the tank cap, the carbon canister or the fuel filler neck.
- If the fuel pressure sensor transmits incorrect parameters to ECU it will also result in the fault code P0440.
How to Fix Error Code P0440?
Each component that may cause a fuel vapor leak should be examined. Sometimes, the solution is simple. Clear the fault code first and then drive your car for at least a day. Follow the other steps if the code appears again.
The fuel tank cap can be replaced easily. Fuel vapours can escape from a damaged or loose fuel tank cap, causing the P0440 error code.
You can also replace the carbon canister or canister with hoses, as well as the vent valve and sensor. Vent solenoids and carbon canisters are easily replaceable parts, but they can wear over time. The P0440 code may be caused by a damaged or malfunctioning filter and/or valve.
Your system may not be malfunctioning. The evaporative emissions control system sensor, like any other part, can wear out. The same fault code can be caused by a damaged sensor. It is therefore a good idea that you check the sensor. Before looking for possible sources of vapour leaks, test the voltage or replace your sensor.
A small hole or cut in the fuel line or evaporative emissions control system hose is likely to be the most complicated solution. Even a small hole in the hose can lead to a large vapour leak that will trigger faulty codes. You should therefore carefully inspect all fuel lines and hoses. To detect leaks, a smoke machine can be used.
How Serious is Fault Code P0440?
The P0440 code will not affect your driving comfort but it will activate the engine fault indicator. Unattended vehicles may fail their emissions test. Leaks in the system may cause fuel vapours to be inhaled and pollution of the environment. Fuel consumption may increase slightly.
