Evaporative Emission Control System Malfunction (P0440)
The P0440 code indicates a general failure in the evaporative emission (EVAP) control system, which prevents fuel vapors from escaping into the atmosphere. This system includes components like the charcoal canister, purge valve, vent valve, and associated hoses. A leak or blockage in any part can trigger this code. Common causes include a loose or missing gas cap, a cracked hose, or a faulty purge solenoid.
01. Most Common Causes
- Loose, damaged, or missing gas cap
- Cracked or disconnected EVAP hoses
- Faulty purge solenoid or vent valve
- Leaking charcoal canister
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible faint fuel odor
- No noticeable drivability issues usually
03. Step-by-Step Diagnosis
Step 1: Inspect and tighten the gas cap; clear the code and see if it returns.
Step 2: Perform a smoke test to locate EVAP system leaks.
Step 3: Check the purge solenoid and vent valve operation with a scan tool.
Step 4: Inspect all EVAP hoses and connections for cracks or disconnects.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but the check engine light will stay on. However, a large leak could allow fuel vapors to escape, which is an emissions violation and may cause a fuel smell.
How much does it cost to fix?▼
The cost varies widely depending on the cause. A simple gas cap replacement costs around $10-$20, while replacing a purge solenoid or canister can range from $100-$300 including labor.