Emissions code
P0440: Fuel vapor system problem
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.
This is a general code for the fuel-vapor system. The computer's self-check could not finish or failed in a way that does not point to one specific part. A loose gas cap is the simplest cause, though valves, hoses or the charcoal canister could also be at fault.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Loose gas cap
Safe to drive; plan to diagnose it before an emissions test.
What you may notice
- Check-engine light on
- Faint fuel smell near the car
- Pump may click off early when fueling
Common causes, most likely first
- Loose gas cap
- Failed purge or vent valve
- Cracked vapor hose
- Canister damage
- Wiring fault in the vapor system
Check this first
Check the gas cap first, then ask the shop which other EVAP codes are stored, since those narrow it down fast.
Other repairs that sometimes fix P0440
| 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).
P0440 questions
Why is this code so vague?
The code names the whole system and not one part. Other stored codes, like leak size or valve circuit codes, help narrow it down, and a smoke test can find the exact leak.
Is it urgent?
Not urgent, but it can hide other problems if left a long time, and most inspections will not pass with the light on. Plan to look at it within a few weeks.
Can a bad gas cap alone trigger it?
Yes, this is often the cause. A cap that is loose, cracked or worn can stop the system from holding pressure. A new one is cheap and always worth trying first.
How much does it cost to fix P0440?
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.
Related codes
- P0455: Large fuel vapor leak
- P0456: Very small fuel vapor leak
- P0442: Small fuel vapor leak
- 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.