Emissions code
P0442: Small fuel vapor leak
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $8 | $40 |
| Labor: 0 to 0.3 hours × $125 to $175 an hour | $0 | $53 |
| Fees: shop supplies, disposal, diagnostics | $0 | $10 |
| Total, rounded | $5 | $110 |
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, gas cap replacement. Which repair your car needs depends on a proper diagnosis.
The computer sealed the fuel-vapor system and watched whether the pressure held. It leaked down a little faster than a pinhole but slower than a missing cap, which points to a small opening such as a tired seal, a loose clamp or a valve that does not quite close.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Worn gas cap seal
Safe to drive; fix at your convenience but before an inspection.
What you may notice
- Check-engine light on
- Faint fuel smell now and then
- No change in how the car drives
Common causes, most likely first
- Worn gas cap seal
- Cracked vapor line or loose clamp
- Purge valve not sealing
- Vent valve stuck
- Damaged canister or hose connection
Check this first
Check that the gas cap clicks and is not cracked. Ask whether the shop will smoke-test before replacing parts.
Other repairs that sometimes fix P0442
| Repair | Typical range, Boston |
|---|---|
| EVAP purge valve replacement | $85 to $260 |
| EVAP vent valve replacement | $120 to $360 |
| 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).
P0442 questions
Does this affect my engine?
No, the engine runs the same. This is a vapor-containment problem, so the only effects are the light, a faint fuel smell at times and a possible inspection failure.
What is a smoke test?
The shop pushes visible, harmless smoke into the vapor system and watches where it escapes. It finds cracked hoses, loose clamps and bad seals quickly, so it saves guessing at parts.
Could the purge valve be the cause?
Yes. If the purge valve sticks partly open it lets vapor leak in a way that looks like a small leak. A shop can test the valve with a scan tool before replacing hoses or the cap.
How much does it cost to fix P0442?
The most common fix, gas cap replacement, has a typical range of $5 to $110 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
P0442 repair cost by city
Related codes
- P0455: Large fuel vapor leak
- P0456: Very small fuel vapor leak
- P0441: Fuel vapor purge flow wrong
- P0446: Fuel vapor vent circuit problem
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.