Evaporative Emission Control System Malfunction
The P0440 code means the vehicle's onboard diagnostic system has detected: Evaporative Emission Control System Malfunction. This is a minor severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $5-$30 for a gas cap; $150-$350 to replace a purge or vent valve at a shop (parts + labor); $300-$700 if the charcoal canister has failed; add a ~$140-$225 diagnostic/smoke-test fee if a shop has to locate the fault
A cracked or loose gas cap causes 60%+ of EVAP codes. This $8 replacement clears P0442, P0455, and P0457 more often than any other repair.
If a new gas cap does not clear it, the leak is somewhere in the EVAP plumbing. A smoke machine finds the exact leak -- a cracked hose, bad seal, or stuck vent valve -- in minutes instead of guessing at parts.
Clear the code after the repair. If the light stays off after 50 miles, you just saved $200+ in shop fees.
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Common Symptoms
- Check Engine Light on
- Fuel odor near the vehicle
- No drivability issues
Probable Causes (Ranked by Likelihood)
- Loose or faulty gas cap Very High
- Leaking EVAP hoses or connections High
- Failed purge solenoid valve Moderate
- Faulty vent control valve Moderate
- Cracked charcoal canister Low
Common Fixes by Vehicle
What techs usually find when diagnosing P0440 on specific vehicles — tap your vehicle for the fix and the exact part:
2007-2017 Toyota Camry/Corolla easy (cap) DIY
P0440 indicates a general EVAP system malfunction. Start with the gas cap -- replace with OE-style Stant. If code returns after 2 drive cycles, perform a smoke test on the entire EVAP system. Common failure points are the VSV (vacuum switching valve) and the charcoal canister vent valve. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 5 min (cap), 1 hour (smoke test + repair)2010-2020 Chevrolet Silverado/Equinox 5.3L/2.4L easy DIY
Check the EVAP purge solenoid (ACDelco) first -- command it open and closed with a scan tool and listen for a click. If it does not click, replace it. Also inspect the EVAP vent valve near the charcoal canister behind the rear axle. A smoke test is the most effective diagnostic method. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 20-30 min2009-2018 Dodge Ram 1500 5.7L Hemi easy (solenoid), moderate (lines) DIY
EVAP system malfunction on the Hemi is commonly caused by a failed purge solenoid (Mopar) or a cracked EVAP line running along the frame rail. Road salt and debris damage the plastic lines. Inspect lines from the fuel tank to the charcoal canister. Dorman replacement line kit includes all fittings and connectors. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30 min (solenoid), 1-2 hours (lines)2004-2018 Nissan Altima/Sentra 2.5L QR25DE moderate DIY
The EVAP canister vent control valve (located near the charcoal canister by the fuel tank) sticks closed or open on Nissan vehicles. Test by applying 12V and checking for a click. Replace with an OE-quality Dorman unit. Also check the EVAP purge volume control solenoid on the intake manifold. Nissan has a service bulletin covering thisa covers full EVAP system diagnostic procedures. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30-45 minFrequently Asked Questions
Is P0440 serious?
No. P0440 is a generic EVAP system malfunction with no drivability impact. The most common cause is a loose gas cap. It will cause an emissions test failure if not addressed.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Inspect and tighten or replace the gas cap as the first step.
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Visually inspect all EVAP system hoses for cracks or disconnection.
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Test purge solenoid with a scan tool by commanding it open and closed.
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Perform a smoke test to locate leaks in the sealed EVAP system.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- Toyota Camry and 4Runner
- Ford F-150
- Chevrolet Silverado
- Honda Accord
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