P0440 minor

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.

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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

Try This First ($8 Fix)

Stant 10838 OE Fuel Cap

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.

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Find the Leak

THIKPO Automotive Smoke Machine

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.

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Clear the Code

ANCEL AD310 OBD-II Scanner

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

Step-by-Step Diagnostic Procedure

Inspect and tighten or replace the gas cap as the first step.
Visually inspect all EVAP system hoses for cracks or disconnection.
Test purge solenoid with a scan tool by commanding it open and closed.
Perform a smoke test to locate leaks in the sealed EVAP system.

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 10838. If code returns after 2 drive cycles, perform a smoke test on the entire EVAP system. Toyota TSB 0116-08 covers EVAP diagnosis. Common failure points are the VSV (vacuum switching valve) and the charcoal canister vent valve.

Labor: 5 min (cap), 1 hour (smoke test + repair)

Common fix part Stant OE Fuel Cap View on Amazon→ Compare fitment at PartsGeek→

2010-2020 Chevrolet Silverado/Equinox 5.3L/2.4L easy DIY

Check the EVAP purge solenoid (ACDelco 214-2149) 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. GM TSB #16-NA-043 covers EVAP system testing. A smoke test is the most effective diagnostic method.

Labor: 20-30 min

Common fix part ACDelco EVAP Purge Solenoid View on Amazon→ Compare fitment at PartsGeek→

2009-2018 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 4891738AB) 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 911-638 replacement line kit includes all fittings and connectors.

Labor: 30 min (solenoid), 1-2 hours (lines)

Common fix part Dorman EVAP Purge Solenoid View on Amazon→ Compare fitment at PartsGeek→

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 Dorman 911-502. Also check the EVAP purge volume control solenoid on the intake manifold. Nissan TSB NTB06-034a covers full EVAP system diagnostic procedures.

Labor: 30-45 min

Common fix part Dorman EVAP Canister Vent Valve View on Amazon→ Compare fitment at PartsGeek→

Frequently 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.