P0446 code meaning
EVAP System Vent Control Circuit
Powertrain system Generic code P04xx codes Check engine light
What P0446 means
The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. The vent valve is normally open and closes for the leak test. By its wording P0446 is its control circuit, and Ford uses it that way for open and shorted circuits. GM, however, uses P0446 for vent system performance – a blocked vent path: while purging with the vent valve open, the tank must not build up vacuum; more than 2989 Pa for 5 s before 4 litres have been purged sets the code, MIL after two trips. GM reports vent circuit faults as P0449, P0498 and P0499. A blocked vent makes refuelling difficult.
P0446 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0446
- Check engine light on
- Refuelling problems, nozzle clicks off early (blocked vent)
- Hissing when opening the fuel cap (vacuum)
- EVAP leak test does not run
Common causes of P0446
- Most likelyVent valve or filter blocked by dirt, dust or water (GM reading)
- PossibleVent valve electrically faulty, coil open or shorted (Ford reading)
- PossibleConnector or wire to the vent valve corroded or open
- PossibleCanister clogged with charcoal or liquid (overfilling)
- Less likelyVent hose kinked or blocked by an insect nest
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP vent valveVent filterCharcoal canisterEngine control module
What each part of P0446 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 46 | The exact fault in that area. |
What to do next
- Note P0446 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0446
What does P0446 mean?
P0446 means "EVAP System Vent Control Circuit". The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. It is a generic code, so it means the same on every make.
Is it safe to drive with P0446?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0446 fail an emissions test?
Yes, it can. P0446 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0446 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0446 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.