P0446 on Mazda: How to Diagnose & Fix
Evaporative Emission Control System Vent Control Circuit
1 Mazda model · 1 documented issue · $800-$1,800 repair
P0446 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…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
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)
P0446 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 P0446 mean on a Mazda?
P0446 stands for "Evaporative Emission Control System Vent Control Circuit." This emissions code points to a problem in the evaporative emission (EVAP) system's vent control circuit, which manages the vent valve that lets the charcoal canister breathe and seals it during leak tests. The EVAP system captures fuel vapors from the tank to keep them out of the atmosphere, and the vent valve must open and close on command for the system to work and self-test. The code sets when the engine computer detects an electrical or performance fault with this vent valve or its circuit. It usually causes only a check engine light with no driveability change, but it does prevent proper EVAP leak monitoring. On Mazda it is documented across 1 model: Mazda5.
What are the most common causes of P0446?
The most common causes of P0446 are: Faulty EVAP vent control valve (solenoid), Wiring or connector fault in the vent valve circuit, Vent valve clogged with dirt, debris, or spider webs, Damaged or corroded vent valve connector, Blocked or pinched vent hose or filter, Faulty charcoal canister assembly, Faulty engine control module driver circuit. The specific cause varies by vehicle.
How much does it cost to fix P0446 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 P0446 on a different make?
View P0446 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.