P0446 on Toyota
Evaporative Emission Control System Vent Control Circuit
P0446 on Toyota vehicles indicates evaporative emission control system vent control circuit. Au7o has documented this code across 6 Toyota models — most commonly on 4Runner, Corolla, FJ Cruiser. 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. Typical repair costs on Toyota range from $15 to $2,500, depending on the specific model and root cause.
Common Causes of P0446
- •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
P0446 on Toyota by Model
Toyota 4Runner(1 issue)
- EVAP System Leak — Charcoal Canister / Vacuum Switching Valve (VSV) Failure (P0440 / P0441 / P0446)1996-2009
EVAP faults (P0440 general malfunction, P0441 incorrect purge flow, P0446 vent control circuit) are among the most common check-engine codes on 3rd- and 4th-gen 4Runners. Toyota issued service bulletin EG013-03 covering these codes across 4Runner/Camry/Tacoma. The frequent culprit is a Vacuum Switching Valve (VSV) — especially the canister-closed-valve VSV near the charcoal canister mounted above the spare tire — which sticks when charcoal fines migrate into it. A loose/failed gas cap or a cracked canister can also trigger the codes.
Toyota Corolla(1 issue)
- EVAP Charcoal Canister and Vent Valve Failure Causing Check Engine Light2000-2008
Corollas in the 9th-generation range commonly develop EVAP system faults from a failing charcoal canister, stuck vent valve, or related vacuum switching valve problems. Owners typically report a persistent check engine light with no major drivability issue, but the vehicle fails emissions inspection and may be difficult to refuel if the vent path is restricted. Toyota service literature and repair databases frequently reference canister-related EVAP diagnosis on these years.
Toyota FJ Cruiser(1 issue)
- A/C Compressor and Evaporator Failure2007-2014
The FJ Cruiser's A/C system is prone to compressor clutch failure and evaporator core leaks. The evaporator is located behind the dashboard, making replacement extremely labor-intensive. The A/C system struggles in hot climates, especially when off-roading at low speeds.
Toyota Highlander(1 issue)
- EVAP Purge Valve / Charcoal Canister Failure — P0441 / P0455 & Fuel-Pump Click-Off2008-2019
The evaporative-emissions system commonly sets P0441 (incorrect purge flow) and P0455/P0446 (large leak / vent malfunction). The vapor canister purge valve (VSV) sticks open or closed, or the charcoal canister breaks down internally and sheds pellets that clog the system. A classic symptom is the gas-pump nozzle repeatedly clicking off before the tank is full, plus a fuel-vapor smell. A loose/failed gas cap or cracked filler-neck boot can also set the codes.
Toyota Sienna(1 issue)
- EVAP System Leak-Detection / Vapor Canister Fault (Check Engine Light, Hard Refueling)2011-2020
Third-generation Siennas commonly throw EVAP (evaporative emissions) faults as the system ages. Failure points include the canister vent solenoid/VSV sticking, the leak-detection pump and reference orifice, the purge valve, and a worn or loose gas cap. Beyond the check engine light and an emissions/smog failure, a stuck-closed vent can make the tank hard to refuel (pump clicks off repeatedly), while a stuck-open vent or cracked line can produce a fuel-vapor smell.
Toyota Tacoma(2 issues)
- A/C Musty/Mold Smell2016-2023
The A/C system can develop a musty or moldy smell when first turned on. This is caused by moisture accumulation and mold/bacteria growth on the evaporator. Common in humid climates and vehicles that use A/C infrequently.
- Evaporative Emissions Leak Faults from Charcoal Canister, Vent Valve, or Filler Neck Corrosion2000-2015
Tacomas in this era commonly develop EVAP system leak faults that trigger a check engine light, often caused by a failing charcoal canister, stuck vent valve, cracked hoses, or a rusted filler neck in salt-belt trucks. Owners usually notice no drivability problem, but the truck will not pass emissions and the light often returns after a gas cap replacement. The pattern is well documented in NHTSA complaints, forum troubleshooting threads, and repair databases.
Looking for P0446 on a different make?
View P0446 across all makes →Frequently Asked Questions
What does P0446 mean on Toyota?▼
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 Toyota specifically, this code is documented across 6 models.
What causes P0446 on Toyota vehicles?▼
Common causes on Toyota: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0446 on a Toyota?▼
Repair costs on Toyota range from $15 to $2,500, depending on the specific model and root cause.
Which Toyota models have P0446 documented?▼
Au7o has documented P0446 on 6 Toyota models: 4Runner, Corolla, FJ Cruiser, Highlander, Sienna, Tacoma.