What does code P0440 mean?

P0440 — General Evaporative Emission (EVAP) system malfunction. Fuel vapors escape to atmosphere instead of being routed to the intake. Belongs to the powertrain.evap system. Severity: info.

What are the common causes of P0440?

Loose or damaged fuel filler cap seal; Cracked EVAP hose — often in the engine bay from heat; Failed purge valve; Cracked charcoal canister; Failed Fuel Tank Pressure (FTP) sensor

Can I drive with code P0440?

Yes, a short trip to the workshop is safe — but do get the code read and don't ignore it.

How do I diagnose P0440?

Read the code and freeze-frame with a scanner, check related-system errors, inspect the components listed (wiring, connectors, sensors). See the "How to diagnose" section above for the full step-by-step.

How do I clear code P0440?

The code can be cleared via an OBD-II scanner (e.g. ELM327 + the Car Diagnostics app): plug the adapter into the OBD port, go to Errors → Clear. If the underlying cause isn't fixed, the code will return within a few drive cycles.

OBD-II Code P0440 — Car Diagnostics Platform

What it means

Common causes

Loose or damaged fuel filler cap seal
Cracked EVAP hose — often in the engine bay from heat
Failed purge valve
Cracked charcoal canister
Failed Fuel Tank Pressure (FTP) sensor
Low intake vacuum affecting purge activation

How to diagnose

01
Read all stored and pending codes with an OBD-II adapter — get the full picture, not just the one code.
02
Capture freeze-frame data (RPM, coolant temperature, engine load) at the exact moment the code triggered.
03
Inspect the named subsystem with our app's AI explanation — get vehicle-specific causes for your make, model and year.

Decode P0440 on your actual car

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