OBD-II Code · Emissions
P0446
EVAP Vent Control Circuit Malfunction
Severity
low
Lowest on our scale. Fix it when convenient.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$100–$300
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
The vent valve in the EVAP system isn't functioning.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Likely causes
- Failed vent valveMost common
- Blocked vent line
- Wiring
Read the full diagnostic procedureP0446 is the vent control circuit code — the canister vent solenoid (CVS) isn't responding correctly to the ECU's open/close commands.
P0446 is the vent control circuit code — the canister vent solenoid (CVS) isn't responding correctly to the ECU's open/close commands. The vent solenoid is what seals the EVAP system during the leak test; when the ECU wants to pull vacuum on the system, it commands the vent solenoid closed and the purge solenoid open. If the vent solenoid is stuck open, stuck closed, electrically faulted, or clogged with debris, the system can't seal and P0446 trips.
The diagnostic ladder
- cap first ($5-30 — even though P0446 fingers the vent circuit, a leaking cap can cause the ECU to log the closest related code on some platforms), then multimeter the vent solenoid for proper resistance and supply voltage, then physically remove the vent solenoid and check it for debris.
- On many vehicles the vent solenoid sits in a position where mud, dust, or insect debris can pack into the vent path and either jam the solenoid or block flow.
- A smoke test with the vent commanded closed verifies the seal.
Vehicle-specific patternsBy platform: 2007-2014 GM full-size trucks (Silverado, Sierra, Tahoe, Yukon, Suburban) are the textbook P0446 vehicle — the canister vent solenoid mo…
By platform: 2007-2014 GM full-size trucks (Silverado, Sierra, Tahoe, Yukon, Suburban) are the textbook P0446 vehicle — the canister vent solenoid mounts near the charcoal canister at the rear of the truck, and the vent line ends near the rear wheel well where it sucks in road dust and mud. The fix is usually a $40-80 vent solenoid plus a clean vent line and sometimes a vent filter retrofit; some shops zip-tie a small filter onto the vent inlet to prevent the next return.
- 2005-2015Toyota/Lexus throws P0446 from a worn vent solenoid that's hit end-of-life mechanically, around 100-150k miles; Toyota sells the part for about $80-150.
- 2003-2010Ford 4.6L can throw P0446 alongside P0442 when the canister cracks and the vent solenoid gets contaminated by canister dust.
- 2008-2015VW/Audi P0446 is usually LDP-related rather than a discrete vent solenoid.
- 2012+Hyundai/Kia P0446 is often a CCV (canister close valve) failure — same idea, different acronym. Repair range: $40-150 vent solenoid replacement, $300-500 LDP on VW/Audi.
Look up another code
P0446 — frequently asked
What does a P0446 code mean?
The vent valve in the EVAP system isn't functioning.
What causes a P0446 code?
Common causes: Failed vent valve; Blocked vent line; Wiring.
What are the symptoms of a P0446 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P0446 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $100-$300.
How do I diagnose a P0446 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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