P0440 on Mazda: How to Diagnose & Fix
Evaporative Emission Control System Malfunction
1 Mazda model · 1 documented issue · $800-$1,800 repair
P0440 on Mazda by model: symptoms, diagnosis and fix
The A/C evaporator core in the Mazda5 develops pinhole leaks from internal corrosion, causing refrigerant loss. The evaporator is located behind the dashboard, making replacement extremely labor-intensive. Corrosion is accelerated by moisture trapped in the cabin air filter area and infrequent cabin filter replacement.
Common Symptoms
- A/C gradually loses cooling capacity over weeks/months
- Oily residue on passenger footwell carpet (refrigerant oil leak)
- Musty smell from vents (moisture buildup around leaking evaporator)
- A/C system needs recharging repeatedly
How to Fix
Replace the A/C evaporator core. This requires dashboard removal, making it one of the most labor-intensive A/C repairs. Replace the receiver/drier, expansion valve, and O-rings at the same time. Regular cabin air filter changes help prevent the moisture buildup that accelerates corrosion.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mazda front A/C evaporator CC43-61-J10OEMMazda CC43-61-J10
Front evaporator core after refrigerant leak localization proves the core is leaking Fitment/availability: The inspected OEM page identifies CC43-61-J10, replacing BPYK-61-J1Z, BP4K-61-J10 and CCY3-61-J1Z, at $587.39 with 1-2-business-da…
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Owner tips & cautions
- TipReplace expansion valve and receiver/drier during evaporator replacement - they are accessible once dash is out
- TipChange cabin air filter every 15,000 miles to reduce moisture buildup around evaporator
- TipRun A/C for 10 minutes monthly to keep seals lubricated and reduce corrosion - Mazda5Club.com A/C thread
Sources for this issue (1)
P0440 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0440 mean on a Mazda?
P0440 stands for "Evaporative Emission Control System Malfunction." This code indicates a general malfunction in the Evaporative Emission Control (EVAP) system, which captures fuel vapors from the gas tank and routes them to be burned by the engine instead of escaping into the air. The computer ran a self-test and detected the sealed vapor system isn't holding pressure or vacuum correctly, often signaling a leak somewhere in the system. The most frequent and easiest cause is a loose or faulty gas cap. The car will run normally, but it will fail an emissions test and may smell faintly of fuel. On Mazda it is documented across 1 model: Mazda5.
What are the most common causes of P0440?
The most common causes of P0440 are: Loose, damaged, or missing gas cap, Cracked or disconnected EVAP hose, Faulty purge valve/solenoid, Faulty vent valve/solenoid, Leaking charcoal canister, Damaged fuel tank filler neck or seal, Faulty leak detection pump or pressure sensor. The specific cause varies by vehicle.
How much does it cost to fix P0440 on a Mazda?
Published repair estimates on Mazda range from $800 to $1,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0440 on a different make?
View P0440 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.