All codes
P0440Emissions System
Evaporative Emission Control System Malfunction
Fix P0440 EVAP system code. Learn what triggers a general EVAP fault and how to track down the source.
What you may notice
Symptoms
- 01Check engine light on
- 02Fuel odor near the vehicle
- 03Failed emissions test
- 04Usually no drivability symptoms
Where to look first
Common causes
- 01Loose, damaged, or missing gas cap
- 02Cracked or disconnected EVAP hose
- 03Faulty purge or vent valve
- 04Leaking charcoal canister
- 05Faulty pressure sensor
Step by step
What to check and repair
- 01Inspect and tighten or replace the gas cap
- 02Smoke test the EVAP system for leaks
- 03Inspect EVAP hoses and connections
- 04Test purge and vent valve operation
- 05Inspect the charcoal canister for cracks
What Does P0440 Mean?
The P0440 code indicates a general malfunction in the EVAP (Evaporative Emission Control) system, which captures and recycles fuel vapors from the tank instead of releasing them into the atmosphere.
A Broad Code
Unlike specific leak codes, P0440 is a general fault. It often points to a leak, a faulty valve, or a sealing problem somewhere in the EVAP system.
Start With the Gas Cap
As with most EVAP codes, a loose or worn gas cap is the easiest and most common cause to check first.
How AI4Car Helps
AI4Car can read EVAP system monitor status and related codes, helping you narrow down whether the fault is a leak, a valve, or a sensor.