P0440
EVAP System Malfunction
low
i Description
The Evaporative Emission (EVAP) system has a general malfunction. The EVAP system captures fuel vapours from the fuel tank and routes them to the engine to be burned, preventing them from escaping into the atmosphere.
? Common Causes
- Loose or damaged fuel cap
- Leaking EVAP hose
- Faulty purge or vent solenoid
- Charcoal canister fault
- Leak in fuel tank or filler neck
! Symptoms
- Check engine light
- Fuel smell near the vehicle
- Failed emissions test
# Diagnostic Steps
- Check fuel cap — tighten or replace if worn
- Smoke-test the EVAP system to find leaks
- Test purge and vent solenoids
- Inspect EVAP hoses for cracks
- Check charcoal canister
⚙ Typical Fix
Replace the fuel cap, repair EVAP hose leaks, or replace a faulty solenoid.
Parts Needed
Fuel cap, EVAP hoses, Purge valve, Vent valve
Estimated Cost
$20-$400
↔ Related Codes
Q Frequently Asked Questions
Yes. EVAP codes do not affect driveability at all. The only impact is environmental (fuel vapours escaping) and emissions test failure.
Start by replacing the fuel cap ($10-$20). If the code returns, a smoke test is needed to find the leak — most DIYers take this to a mechanic.
Fuel cap: $10-$20. Purge/vent valve: $30-$100. EVAP hose: $20-$50. Smoke test: $80-$120 at a shop.
☞ Learn More
- Check Engine Light — What it means, is it safe to drive & how to fix
- What is OBD-II? — Complete guide to your car's diagnostic system
- How to Read DTC Codes — Step-by-step with a Bluetooth scanner
- OBD-II Scanner Buying Guide — Find the best scanner for your car