P0440
Evaporative Emission Control System Malfunction
Quick answer: P0440 means evaporative Emission Control System Malfunction. Fixing the underlying cause typically runs $0 to $780 at an independent shop. Usually safe to drive.
- Severity
- Low
- Safe to drive?
- Usually safe to drive
- Typical repair
- $0 to $780
- Most likely cause
- A loose, aged, or poorly sealing gas cap (still the first thing to rule out, and free)
What P0440 means
P0440 is the evap system's general-purpose complaint: the sealed fuel-vapor system failed its self-test, but the computer is not saying specifically whether the problem is a large leak, a small leak, or a component that would not respond. Think of it as the header on the story rather than the story itself, and it often arrives alongside a more specific code like P0442 or P0455 that narrows things down. When it appears alone, the same suspects apply, starting with the humble gas cap.
Common symptoms
What drivers usually notice with this code.
- Check-engine light with no change in how the car drives
- Occasionally a faint fuel smell near the car after filling up
- Failed emissions test
- The light sometimes appearing within a day or two of a fill-up
- No other symptoms at all in most cases
Common causes
Ranked from most to least likely.
- 1A loose, aged, or poorly sealing gas cap (still the first thing to rule out, and free)
- 2A cracked or disconnected evap hose, which turn brittle with age
- 3A purge valve stuck open or closed, failing the system's self-test
- 4A failed vent valve, often victimized by road grime where it sits near the tank
- 5A cracked charcoal canister or its fittings
- 6A wiring or sensor fault in the evap monitoring circuit
Can I keep driving?
Yes, this is an emissions housekeeping code with no effect on how the car runs, so drive normally and deal with it before your next emissions test.
Severity: Low. A flashing check-engine light always means stop, whatever the code says.
Ballpark cost
What P0440 usually costs to fix
A range, not a quote. What you pay depends on your vehicle, your area, and which of the causes above turns out to be the real one.
Typical parts and labor at an independent shop. Dealer rates run higher.
That spread is wide on purpose. P0440 points at a system, not a single part, so the real answer depends on what the diagnosis finds. Use the range to know what to expect. If an estimate comes in higher, it usually means the specific repair is more involved, and it is always fair to ask what is included.
Next steps
What to do next
Reseat your gas cap firmly, wipe its seal clean, and give it a few days of driving; a meaningful share of these clear on their own. If the light returns, ask the shop to pull all stored codes, because a companion code often names the real problem, and an evap smoke test finds what the codes do not. Insist on seeing which component failed before replacing anything, since this system has a reputation for parts being swapped on guesswork.
Walk in informed
Ask for the diagnosis in writing and which test confirmed it, so you understand exactly what is being fixed. Fixxr shows you what the job typically costs near you, so you can approve the work with confidence.
Sources & further reading
- NHTSA — Check for vehicle safety recalls — look up open recalls for your vehicle by VIN, free
- FTC — Auto repair basics — your consumer rights at the repair shop
- AAA — Car repair and maintenance costs — independent guidance on what repairs should cost
Cost ranges and guidance reviewed July 2026.
P0440 FAQ
P0440 questions, answered
Can I drive with a P0440 code?
Yes, this is an emissions housekeeping code with no effect on how the car runs, so drive normally and deal with it before your next emissions test.What does the P0440 code mean?
P0440 is the evap system's general-purpose complaint: the sealed fuel-vapor system failed its self-test, but the computer is not saying specifically whether the problem is a large leak, a small leak, or a component that would not respond. Think of it as the header on the story rather than the story itself, and it often arrives alongside a more specific code like P0442 or P0455 that narrows things down. When it appears alone, the same suspects apply, starting with the humble gas cap.What are the most common causes of a P0440 code?
The most likely causes, roughly in order, are a loose, aged, or poorly sealing gas cap (still the first thing to rule out, and free); a cracked or disconnected evap hose, which turn brittle with age; a purge valve stuck open or closed, failing the system's self-test; a failed vent valve, often victimized by road grime where it sits near the tank. Reseat your gas cap firmly, wipe its seal clean, and give it a few days of driving; a meaningful share of these clear on their own. If the light returns, ask the shop to pull all stored codes, because a companion code often names the real problem, and an evap smoke test finds what the codes do not. Insist on seeing which component failed before replacing anything, since this system has a reputation for parts being swapped on guesswork.How much does it cost to fix a P0440 code?
Fixing the underlying problem behind a P0440 code typically runs $0 to $780 at an independent shop, including parts and labor. The exact figure depends on your vehicle and which part turns out to be at fault.
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