P0440Low severityEmissionsDIY: Easy
P0440: Evaporative Emission Control System Malfunction
A general EVAP system fault — somewhere in the fuel vapor recovery loop there's a leak or component failure. Start with the gas cap.
Can I keep driving?
Yes. It does not affect drivability, but it will fail an emissions test.
Symptoms you might notice
- Check engine light with no other change in how the car runs
- Sometimes a faint fuel smell
What to check first
- Check the gas cap seal and tighten it until it clicks.
- Look for more specific EVAP codes stored with it (P0442, P0455, or a purge or vent valve code). They narrow down where to look.
- Inspect the EVAP hoses and the charcoal canister near the tank for cracks.
- A smoke test at a shop is the quickest way to find a small leak if the visual check turns up nothing.
Most common causes
- Loose gas cap
- Cracked charcoal canister
- Failed purge solenoid
Check it against your exact vehicle
A code means the same thing on every car, but where the parts are and what to check first depends on your year, make, model and engine. Tell CaliperAI what you are seeing and it will help narrow down the likely causes for your vehicle.
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General information about this code, not a diagnosis of your specific vehicle. Safety-critical work such as brakes, fuel and airbags is best left to a qualified mechanic.