P0440 code meaning
EVAP System
Powertrain system Generic code P04xx codes Check engine light
What P0440 means
The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. P0440 is the general code for a fault in this system without further narrowing down – leak, purge flow or component. Today most makers use the specific codes instead (P0441 ff, P0455–P0457, P0496); the GM and Ford tables of 2006–2023 do not contain P0440. It appears in VW code lists and in an FCA bulletin for the Alfa Romeo 2.0, fixed by software, where FCA calls it incorrect flow. What sets it is therefore manufacturer-specific; CARB requires purge flow and leaks to be monitored.
P0440 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.2 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0440
- Check engine light on
- Possibly slight fuel smell
- Readiness or emission inspection not passed
- No change in driving
Common causes of P0440
- Most likelyFuel cap leaking, loose or wrong
- PossiblePurge valve leaking or sticking
- PossibleLeaking or cracked EVAP hoses, canister or vent valve
- Less likelyEngine module software
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP systemFuel capEVAP purge valveCharcoal canister
What each part of P0440 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 40 | The exact fault in that area. |
What to do next
- Note P0440 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0440
What does P0440 mean?
P0440 means "EVAP System". The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. It is a generic code, so it means the same on every make.
Is it safe to drive with P0440?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0440 fail an emissions test?
Yes, it can. P0440 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0440 to fix?
Difficulty: medium. A typical repair takes 0.2 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0440 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.