What does it mean?
This diagnostic code (DTC) is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II. Although generic, specific repair steps may vary by make/model.
It indicates that a part of the EVAP control system is no longer functioning properly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses.
The Evaporative Emission Control (EVAP) system prevents fuel vapors from escaping from a vehicle’s fuel system. Fuel vapors are routed through hoses to a charcoal canister for storage. Later, when the engine is running, a purge control valve opens, allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms
You will likely not notice any driving issues.
Causes
A P0440 code could mean that one or more of the following events have occurred:
The gas cap is not installed or is not working properly
The purge solenoid is faulty
The canister is clogged and not working properly
Possible Solutions
With an OBD-II P0440 trouble code, diagnosis can sometimes be difficult. Here are some tips to try:
Remove and reinstall the gas cap, clear the code, and drive for a day to see if the codes return.
Inspect the EVAP system for cuts/holes in the tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks
P0440 Repair Video
We are not affiliated with the producers of this diagnostic video, but we found it to be of excellent quality and worth sharing!
Other EVAP DTCs: P0441 – P0442 – P0443 – P0444 – P0445 – P0446 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456