P0446: Evaporative Emission Vent Control Circuit Malfunction
A fault in the EVAP vent valve circuit. The vent valve seals the canister against atmosphere during the leak test; without it, the test cannot pull a vacuum and may set false leak codes alongside.
What P0446 means
P0446 is a generic OBD-II powertrain code in the emissions group. In plain English: the computer found an electrical fault in that circuit: an open, short or bad connection, or a failed component.
- Check engine light
- Usually on
- Emissions-related
- Yes — can fail inspection
- Limp mode possible
- Not typical
- Drive cycle to clear
- Required
Get it fixed
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Symptoms
- Check engine light on
- Possible smell of fuel near tank or engine bay
- Failed emissions inspection
- Loose-cap warning may appear
Common causes
- 01Vent valve seized or contaminated by water/dirtMost likely
- 02Wiring or connector faultPossible
Can I drive with P0446?
Generally yes.
This fault is unlikely to affect how the car drives, but it will usually fail an emissions inspection. Fix it when convenient.
Why we rate it low
- Turns on the check engine light
- Emissions-related: will usually fail an OBD inspection
- EVAP leaks rarely affect how the car drives
- Needs a drive cycle to confirm a repair
Severity is our rule-based rating from the code’s flags in OBDex and the system it affects, not an inspection of your car. If the check engine light is flashing, or you notice overheating, low oil pressure, or brake or steering problems, stop driving and get help.
How to diagnose P0446
- 1
Confirm the code and save freeze-frame data
Read the codes with an OBD-II scan tool and note every code, not just P0446. Save the freeze-frame data (speed, load, temperature when the fault set) before clearing anything; it tells you when the fault happens.
- 2
Fix other faults first
If other codes are stored, start with power-supply, sensor-circuit and communication codes. They can cause this code as a side effect.
- 3
Test the circuit
Inspect the wiring and connector at the evap vent valve and evap vent valve wiring for damage, corrosion or chafing. With a multimeter, check supply voltage, ground and signal against the specifications in the service manual for your vehicle.
- 4
Test the likely causes in order
Start with the most likely cause and work down: Vent valve seized or contaminated by water/dirt; wiring or connector fault. Test before replacing parts.
- 5
Check for recalls and service bulletins
Look up recalls for your exact vehicle with its VIN, and ask a dealer about technical service bulletins (TSBs). Manufacturers sometimes issue software updates or extended warranties for known faults.
- 6
Clear the code and verify the repair
After the repair, clear the code and complete a full drive cycle (cold start, idle, steady highway cruise, deceleration). The code is fixed when the related readiness monitor completes without it returning.
P0446 repair cost estimate
Estimate, not a quote. Labor times are typical ranges for this code from OBDex, and $125/hr is an assumed rate. Shop rates and labor times vary by vehicle and region. Diagnosis time may be billed separately.
- DIY difficulty
- Easy
- Good DIY job?
- Yes, with a scan tool
Basic hand tools; a common first DIY job.
Parts and systems involved
- EVAP vent valve
- EVAP vent valve wiring
P0446 FAQ
What does P0446 mean?
P0446 means “Evaporative Emission Vent Control Circuit Malfunction”. A fault in the EVAP vent valve circuit. The vent valve seals the canister against atmosphere during the leak test; without it, the test cannot pull a vacuum and may set false leak codes alongside.
Is P0446 serious? Can I keep driving?
We rate P0446 as low severity. Generally yes. This fault is unlikely to affect how the car drives, but it will usually fail an emissions inspection. Fix it when convenient.
What causes P0446?
The most common causes, from most to least likely: Vent valve seized or contaminated by water/dirt; Wiring or connector fault. Test before replacing parts, because several causes can set the same code.
How much does it cost to fix P0446?
Typical labor is about $40–$190 at an assumed $125/hour shop rate, plus parts. That is an estimate, not a quote: labor times and rates vary by vehicle and region, and diagnosis may be billed separately.
Can I fix P0446 myself?
DIY difficulty is easy. Many owners can handle it with a scan tool, a multimeter and basic hand tools. Always confirm the cause before buying parts.
Will P0446 clear itself?
Once the fault is fixed, the check engine light usually goes off by itself after the system passes its self-test over several drive cycles. Clearing the code with a scan tool resets readiness monitors, so an inspection station may turn you away until a full drive cycle is completed.