Nissan Altima P0455
TL;DR
P0455 is a large EVAP leak. On the Altima the usual suspects are a loose or bad fuel cap, a cracked EVAP hose, or a failed vent/purge valve. Low severity; safe to keep driving.
Why P0455 shows up on the Nissan Altima
The Altima's EVAP system seals fuel vapors inside the tank and charcoal canister, then purges them into the engine to be burned. When the computer runs a leak test and finds a large leak it can no longer hold vacuum or pressure in the system, so it stores P0455 and turns on the check engine light. Because the Altima is a high-volume sedan often driven for years with the same fuel cap, a degraded or improperly tightened cap is by far the most reported trigger.
Model-typical causes and rough likelihood
- Loose or worn fuel cap (commonly the cause) — the seal hardens with age or the cap is not clicked tight after refueling.
- Cracked or disconnected EVAP hoses — rubber lines near the tank and canister can dry out and split, often reported on higher-mileage cars.
- Faulty EVAP vent control valve or purge valve — a valve stuck open reads as a large leak.
- Charcoal canister or gas cap area damage — less common, sometimes after overfilling the tank.
What owners should check first
Before spending money, remove the fuel cap, inspect the rubber seal for cracks, wipe it clean, and re-tighten until it clicks several times. Drive a few days and see if the light clears on its own. If it returns, have a shop perform an EVAP smoke test, which pinpoints the leak quickly instead of replacing parts by guesswork.
Is it urgent?
No. P0455 will not damage the engine or leave you stranded. Fix it at your convenience, but do address it before any emissions inspection.
Summary
| Code | P0455 |
|---|---|
| Meaning | EVAP System Leak Detected (Large Leak) |
| Severity | Low |
| Can I drive? | Yes, safe to drive normally |
| Most common cause | Loose or worn fuel cap |
| Typical repair cost | $15–$400 depending on part |
Full diagnostics
For the complete step-by-step diagnostic and repair guide, see P0455 — full diagnostics.
Frequently asked questions
Can I keep driving my Nissan Altima with a P0455 code?
Yes. P0455 on a Nissan Altima is a low-severity EVAP (evaporative emissions) fault that does not affect engine power, safety, or drivability. You can continue driving normally, but the check engine light will stay on and the car may fail an emissions test until the leak is repaired.
What is the most common cause of P0455 on a Nissan Altima?
The most commonly reported cause on the Nissan Altima is a loose, worn, or missing fuel cap that no longer seals the EVAP system. Other frequent causes include cracked EVAP hoses near the fuel tank and canister, and a faulty EVAP vent or purge valve stuck open.
How much does it cost to fix P0455 on a Nissan Altima?
If the fault is only a fuel cap, the repair is roughly $15 to $40 for a new cap. If a hose or EVAP valve is at fault, expect about $150 to $400 including diagnosis and an EVAP smoke test at a shop. Costs vary by region and labor rates.