OBD-II Car P0455 Error
What it means
P0455 means the engine computer has detected a large (gross) leak in the evaporative emission control system, known as the EVAP system. The EVAP system captures fuel vapors from the gas tank and routes them to be burned in the engine instead of escaping into the air. To check for leaks, the computer pressurizes or applies vacuum to the system; if it cannot hold that pressure, it sets a leak code. P0455 specifically points to a large leak — most often something as simple as a loose, missing, or worn gas cap, but it can also be a cracked hose or a stuck-open valve. The usual symptom is just a check engine light; sometimes you may notice a faint fuel smell near the gas cap. The car normally drives and runs the same.
The bottom line on the P0455 error
P0455 flags a large EVAP (fuel-vapor) leak, and despite sounding serious the culprit is most often just a loose, missing, or worn gas cap, nothing major. The car drives normally, there's no rush — but clearing the code won't help; it returns once the computer reruns its leak test.
Start with the cheapest move: re-seat the gas cap until it clicks, or replace it for under $25 — that cures about half of cases. If the light returns, inspect the EVAP hoses and valves, and pay a shop for a smoke test ($100–$300) only when the cap and visible lines check out.
P0455 snapshot
Our own at-a-glance triage of the P0455 error, from the verified data on this page. See error-code rankings → · How we score →
Common causes of the P0455 error
- Loose, missing, cracked, or worn gas cap (by far the most common cause)
- Cracked, disconnected, or rotted EVAP hoses
- Stuck-open EVAP canister purge valve or vent valve
- Damaged or cracked charcoal canister
- Cracked or damaged fuel filler neck or fuel tank
- Faulty leak detection pump (on systems that use one)
Which OBD-II cars get the P0455 error
P0455 appears on nearly all OBD-II vehicles but is reported especially often on GM/Chevrolet models (Equinox, Silverado) and on Nissan/Infiniti platforms — the Infiniti QX80, Nissan Titan, and Xterra are known for EVAP vent-valve failures that trigger a gross-leak code. A loose or missing gas cap is the single most common trigger across every make.
How to fix the OBD-II Car P0455 error
- 1Tighten or replace the gas cap firstRemove the gas cap, check the rubber seal for cracks or dirt, and re-seat it until it clicks several times. A loose or worn cap is the number-one cause of P0455. If the cap is damaged or its seal is hardened, replace it with the correct cap for your vehicle — it is the cheapest possible fix.
- 2Clear the code and drive a few cyclesAfter tightening or replacing the cap, clear the code with a scan tool (or let the car complete several drive cycles). The light may take a day or two of normal driving to turn off on its own if you simply re-tightened the cap. If it returns, move on to inspecting hoses and valves.
- 3Inspect EVAP hoses and connectionsVisually trace the EVAP hoses from the gas tank to the charcoal canister and engine. Look for cracked, brittle, or disconnected lines and loose clamps. A large leak is often easy to spot or hear once the system is under test.
- 4Test the purge and vent valvesA purge or vent valve stuck open creates a large leak. A shop can use a smoke machine to pinpoint exactly where vapor escapes and test whether the valves seal and open on command. This is the most reliable way to find a leak that is not the gas cap.
🧰 When to call a professional
Call a professional if the code returns after replacing the gas cap and inspecting the visible hoses, or if you do not have access to a smoke machine. EVAP leaks can be hard to find by eye, and a smoke test quickly reveals cracked hoses, a leaking canister, or a stuck valve that would otherwise be guesswork.
OBD-II P0455 vs OBD-II P0442 vs OBD-II P0440: how they compare
How this code stacks up against related error codes for difficulty, urgency, and cost.
| OBD-II P0455 | OBD-II P0442 | OBD-II P0440 | |
|---|---|---|---|
| DIY difficulty (1–5) | 2 | 2 | 2 |
| Urgency (1–5) | 2 | 2 | 2 |
| Typical cost | $ | $ | $ |
How much does it cost to fix the P0455 error?
| DIY parts only | $0–$80 |
| Professional diagnosis & repair | $100–$300 |
| If major component | $250–$600 |
Repair or replace?
Like other EVAP codes, this is usually cheap and rarely justifies replacing expensive parts — roughly half of P0455 cases are cured by simply re-seating or replacing the gas cap for well under $25. A stuck vent valve or cracked hose is the next-cheapest DIY fix, and only a damaged charcoal canister or filler neck runs into the hundreds. The car drives normally, so plan the repair calmly; pay a shop for a smoke test only if the gas cap and visible hoses check out and the leak is still hiding.
Common replacement parts for the P0455 error
| Gas cap | $10–$50 | Fixes about half of all cases | |
| EVAP vent valve/solenoid | $30–$80 | Common failure on Nissan/Infiniti | |
| EVAP vapor hose | $10–$50 | For cracked or disconnected lines | |
| Charcoal canister | $80–$200 | Only if the canister itself is cracked |
Prices are typical retail ranges and vary by model and supplier — always confirm the exact part number for your appliance before buying.
OBD-II P0455 error — FAQ
＋ − Is it safe to drive with this code?
Yes. P0455 is an emissions code, not a safety or driveability code — the car will run and drive normally. The main downsides are that it releases fuel vapors into the air and you will fail an emissions/smog test until it is fixed. Still, get it checked, since the light can hide other problems if you leave it on.
＋ − How much does it cost to fix?
Often very little. A new gas cap is roughly $15–$50 and frequently solves it. If a hose, purge valve, or vent valve is at fault, repairs typically run $100–$300 including labor. Replacing a charcoal canister or fuel filler neck is more, and a damaged fuel tank (rare) can reach several hundred dollars.
＋ − Can I just reset the code and ignore it?
Clearing the code turns the light off temporarily, but it will return once the computer re-runs its EVAP leak test if the leak is still there. The fix is usually cheap (a gas cap), so it is worth addressing rather than repeatedly resetting it — and you cannot pass an emissions test with an active EVAP fault.
Sources & manufacturer references
This guide is independently written and not affiliated with OBD-II. Always unplug appliances before servicing and follow your model's manual. Error codes and steps can vary by model — when in doubt, consult a qualified technician.