Emissions code
P0446: Fuel vapor vent circuit problem
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $35 | $130 |
| Labor: 0.7 to 1.2 hours × $125 to $175 an hour | $88 | $210 |
| Fees: shop supplies, disposal, diagnostics | $0 | $20 |
| Total, rounded | $120 | $360 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in Boston, $31.54 an hour, times 4 to 5.5 to cover what a shop bills (overhead, tools, insurance, profit). Parts are a band from budget aftermarket to the manufacturer part. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
This is the range for the most common fix, evap vent valve replacement. Which repair your car needs depends on a proper diagnosis.
The vent valve lets fresh air into the vapor system when the tank needs it. The computer tested the valve and its circuit and found it did not open or close when told. A blocked vent can build pressure in the tank and make fueling slow or messy.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Vent valve stuck shut
Usually safe, though a stuck vent valve can make filling the tank slow and clicky.
What you may notice
- Check-engine light on
- Gas pump shuts off early
- Hard to fill the tank
Common causes, most likely first
- Vent valve stuck shut
- Valve clogged with dirt or water
- Pinched or blocked vent hose
- Wiring or connector fault
- Failed canister
Check this first
If the gas pump keeps clicking off while you fill up, tell the shop. That is a strong clue the vent path is blocked.
Other repairs that sometimes fix P0446
| Repair | Typical range, Boston |
|---|---|
| Gas cap replacement | $5 to $110 |
| EVAP purge valve replacement | $85 to $260 |
| Diagnostic scan (check engine light) | $60 to $290 |
Before you pay
- Ask the shop what test showed this part is the cause, not just that the code appeared.
- Ask for parts and labor listed separately, and for the hours.
- Ask for a written OK before any extra work. Massachusetts rules require written authorization before repairs.
Got a quote already? Check it against the range. Want to see if your car has a recall tied to this problem? Check recalls by VIN.
Need to read a code yourself? OBD-II scanners on eBay (affiliate link, disclosure).
P0446 questions
Why does the pump keep clicking off?
The tank cannot push air out through the blocked vent, so the fuel nozzle senses back-pressure and shuts off early. It is a strong sign of this code, so tell the shop if the pump keeps stopping.
Where is the vent valve?
It sits near the charcoal canister, often under the back of the car near the tank, where road grit and water can reach it. Many shops need to lift the car, which adds a little to the labor.
Does a car wash or deep water hurt it?
They can over time. Dirt and moisture can clog the valve, and in snowy areas road salt speeds up corrosion. Avoid pressure washing under the rear of the car and keep the area rinsed gently.
How much does it cost to fix P0446?
The most common fix, evap vent valve replacement, has a typical range of $120 to $360 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
P0446 repair cost by city
Related codes
- P0449: Fuel vapor vent valve circuit problem
- P0455: Large fuel vapor leak
- P0441: Fuel vapor purge flow wrong
- P0442: Small fuel vapor leak
More emissions codes
Code meaning written in our own words. Some codes mean different things on different makes, so check your scan tool or manual. Not a repair shop, estimates only.