P0446: How to Diagnose & Fix — Evaporative Emission Control System Vent Control Circuit
15 vehicles · 8 makes · $20-$1,800 repair
How to diagnose and fix P0446: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chrysler 300 · 2011–2023
Evaporative emission control system develops small leaks triggering P0456 code. Most commonly failed gas cap, chaffed EVAP purge pipe harness, or failed purge solenoid. Triggers check engine light and prevents emissions testing pass.
Common Symptoms
- Check engine light with P0456 code
- "Gas cap" warning even with cap tight
- Fuel smell near vehicle
- Failed emissions test
- No performance or drivability issues
How to Fix
Start with gas cap replacement ($20-40). If code returns, smoke test EVAP system to locate leak. Common fixes: replace purge solenoid, repair chaffed wiring harness, or replace cracked EVAP hoses.
Sources for this issue (1)
Dodge Journey · 2009–2020
AC compressor fails due to inadequate lubrication, leaky seals, and internal mechanical failure. Evaporator develops leaks from age and moisture. Condenser prone to damage from road debris. Lack of lubrication from leaks causes compressor seizure.
Common Symptoms
- AC blows warm air
- AC works intermittently
- Compressor clutch not engaging
- Loud grinding or squealing from compressor
- Musty odor from vents (evaporator mold)
How to Fix
Diagnose AC system to identify leak source. Replace failed compressor ($400-800), evaporator ($300-600), or condenser ($200-400) as needed. Flush AC system when replacing compressor. Replace receiver/drier whenever system opened.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mopar 55111410AF complete A/C compressor
Replace a compressor confirmed failed on the listed configuration Fitment: 2016-2020 Journey 2.4L on the product fitment table; not the 3.6L compressor Live OEM direct-product page when checked
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Sources for this issue (1)
Toyota Highlander · 2008–2019
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.
Common Symptoms
- Check engine light P0441 / P0455 / P0446
- Gas pump clicks off repeatedly while fueling
- Fuel/vapor odor
- Slight rough idle after refueling
- Failed emissions/EVAP test
How to Fix
Start with the cheapest causes: reseat/replace the fuel cap and inspect the filler-neck boot. Test the purge VSV and vent valve; replace the sticking solenoid (e.g., Genuine duty vacuum switching valve 90910-12276 on 2009 3.5L applications, now superseded — verify by VIN as part numbers were superseded). If charcoal is contaminating the lines, replace the vapor canister and clear the pellets from the purge/vent circuit.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 90910-12204 genuine duty vacuum switching valve
replacement purge/VSV only after testing proves this engine-specific valve sticks, leaks or fails to actuate Fitment/availability: VIN-confirmed 2008-2013 Highlander gas 3.5L 2GR-FE purge/VSV branch whose Toyota diagram calls for 90910-1…
- Toyota 90910-12276 genuine duty vacuum switching valve
replacement purge/VSV after electrical, sealing and flow testing identifies this exact valve Fitment/availability: VIN-confirmed Highlander gas branch whose current vacuum-piping diagram calls for 90910-12276 or 90910-TC001; the reviewed…
- Toyota 77740-0E020 genuine charcoal canister assembly
replacement canister only after smoke/flow testing or visible charcoal contamination proves the canister is leaking, restricted or breaking down Fitment/availability: VIN-confirmed 2008-2013 Highlander gas ASU40/GSU40/GSU45 branch; repla…
- Toyota 77300-06040 genuine fuel-tank cap assembly
lowest-cost replacement only when inspection or cap testing confirms a damaged seal, ratchet or sealing surface Fitment/availability: VIN-confirmed 2008-2013 Highlander branch using 77300-06040; verify emissions package and current super…
- Toyota 77300-07030 genuine fuel-tank cap assembly
replacement cap only when the later-generation cap or seal is proven unable to hold the EVAP test pressure Fitment/availability: VIN-confirmed 2014-2017 Highlander gas ASU50/GSU50/GSU55 branch; Hybrid and later vehicles have separate cat…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
Kia Rio · 2001–2011
Toyota Sienna · 2011–2020
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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?
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.
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?
Repair costs for P0446 range from $20 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by P0446?
Au7o has documented P0446 across 15 vehicle models from 8 manufacturers: Chevrolet, Chrysler, Dodge, Ford, Kia, Nissan, Pontiac, Toyota.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.