Honda Accord P0455
TL;DR
P0455 is a large EVAP leak on the Accord, most often a loose or worn fuel cap, sometimes a cracked EVAP hose or failed vent/purge valve. Low severity, safe to drive, fix soon to pass emissions.
Why P0455 shows up on the Honda Accord
The Honda Accord uses a sealed EVAP system that stores gasoline vapors in a charcoal canister and later burns them in the engine. A large leak means vapor is escaping somewhere it should not, so the pressure or vacuum test the car runs on itself fails and sets P0455. On the Accord this is usually a simple sealing problem rather than an engine fault, which is why the code is rated low severity.
Model-typical causes and rough likelihood
- Loose, cross-threaded, or worn fuel cap (around 40-50%) — the number-one cause; the rubber seal hardens with age and stops sealing.
- Cracked or disconnected EVAP hose (around 20%) — rubber lines near the canister and fuel tank get brittle with heat and age.
- Faulty vent valve or canister assembly (around 15%) — commonly reported on higher-mileage Accords, sometimes after driving on dusty roads.
- Purge valve stuck open (around 10%) — can also cause rough idle alongside the code.
- Damaged filler neck or fuel tank seal (less common).
Owner tips before you pay a shop
First, park, remove the fuel cap, inspect the rubber gasket for cracks, then screw it back on until it clicks at least three times. Clear the code or simply drive 3-5 days of mixed driving so the EVAP monitor can re-run. If the light returns, a genuine Honda fuel cap is an inexpensive first replacement. A mechanic can confirm larger leaks with a smoke test, which pushes visible vapor through the system to reveal the leak point quickly.
Summary
| Code | P0455 |
|---|---|
| Meaning | EVAP system large leak detected |
| Severity | Low |
| Can I drive? | Yes, safe to drive; fix to pass emissions |
| Most common cause | Loose or worn fuel cap |
| Typical repair cost | $20-$60 (cap) to $150-$450 (hose/valve) |
Full diagnostics
For the complete step-by-step diagnostic and repair guide, see P0455 — full diagnostics.
Frequently asked questions
Is it safe to keep driving my Honda Accord with a P0455 code?
Yes. P0455 on the Honda Accord is a low-severity emissions code that does not affect engine performance, safety, or fuel economy in any meaningful way. The car will drive normally. However, the check engine light will stay on, which can hide other new codes and will usually cause you to fail a state emissions or smog test, so you should have it repaired within a week or two.
What is the most common cause of P0455 on a Honda Accord?
The most common cause of P0455 on a Honda Accord is a loose, worn, or improperly sealed fuel cap. The rubber gasket on the cap hardens over the years and stops sealing the EVAP system, which triggers a large-leak code. The simplest first step is to remove the cap and reinstall it until it clicks several times, or replace it with a genuine Honda cap, which is an inexpensive fix.
How much does it cost to fix P0455 on a Honda Accord?
For a Honda Accord, fixing P0455 typically costs between 20 and 60 USD if it is only a new fuel cap, which many owners install themselves. If the problem is a cracked EVAP hose, a failed vent valve, or a purge valve, professional repair usually runs about 150 to 450 USD including diagnostic smoke testing and parts. Costs vary by region and by which specific component is leaking.