As an Amazon Associate we earn from qualifying purchases. This means we may earn a commission, at no extra cost to you, on products you buy through links on this page.
What it meansAn EVAP leak traced specifically to the fuel cap — loose, missing, or not sealing.
Most likely fixTighten the cap until it clicks; replace it if the seal is worn.
Safe to drive?Yes — no effect on how it drives, but it won't pass emissions.
Typical cost$0–$20 (a gas cap, or free if it just needed tightening).
P0457 is the EVAP code that points straight at the gas cap. Re-seat the cap until it clicks at least once and drive a day or two — it usually clears on its own. No scan tool or shop visit needed unless a new cap doesn't fix it.
What P0457 means
P0457 stands for “Evaporative Emission System Leak Detected (Fuel Cap Loose/Off).” Of all the EVAP codes, this is the one that points most directly at a single, cheap part — the gas cap. Your Honda’s EVAP system has to stay sealed to trap fuel vapor, and a cap that wasn’t clicked tight, or whose rubber seal has hardened with age, lets vapor escape and trips P0457 along with the check engine light.
The fix is the easiest on the car: re-seat the cap until it clicks at least once and drive for a day or two. The code typically clears itself once the system confirms a seal — no scan tool required. If a properly tightened, good-condition cap doesn’t fix it, replace the cap with a genuine Honda or OEM-spec one (around $10–$20). For the full walkthrough, see the Honda Check Fuel Cap guide.
If even a new cap doesn’t clear it, the leak may be slightly larger than the cap — look at the related codes P0455 (large EVAP leak) and P0456 (small EVAP leak), and check the filler-neck sealing surface.
Common causes most common first
Gas cap not tightened until it clicks
Worn or cracked gas cap seal (hardens with age)
Wrong or low-quality aftermarket cap that won't seal
Damaged filler-neck sealing surface or threads
Cap left off or loose after fueling
Do these checks first
Remove and re-seat the cap, turning until it clicks at least once, then drive 1–2 days to let the system re-test.
Inspect the cap's rubber seal for cracks or hardening; replace the cap if it looks worn.
Fit a genuine Honda or quality OEM-spec cap — cheap caps often don't seal.
Check the filler neck where the cap seats for dirt, damage, or a deformed lip.
Usually nothing — just tightening the cap. If the cap is worn, a genuine Honda or quality replacement is about $10–$20, which is the cheapest fix on the car.
Advertisement
FAQ
What does the P0457 code mean on a Honda?
P0457 means the engine computer detected an evaporative emissions (EVAP) leak traced specifically to the fuel cap — it's loose, missing, worn, or not sealing. It's the most cap-specific of the EVAP leak codes, so the fix is almost always the gas cap itself.
How do I fix a P0457 code on my Honda?
Re-seat the gas cap, turning it until it clicks at least once, then drive normally for a day or two — the code usually clears on its own once the system confirms a good seal. If the cap's rubber seal is cracked or hardened, replace it with a genuine Honda or quality OEM cap for about $10–$20.
Is it safe to drive with a P0457 code?
Yes. A P0457 fuel-cap leak doesn't affect how the engine runs, your safety, or fuel economy — you're only venting a little fuel vapor. The only practical downside is it won't pass an emissions test until it's resolved, so tighten or replace the cap and keep driving.
I tightened the gas cap but the P0457 code is still there — why?
Two reasons: the system can take a day or two of driving to re-test and clear the code, and if the cap's seal is cracked or hardened it won't seal even when tight. Replace the cap with an OEM-spec one. If it still won't clear after a new cap, check the filler-neck sealing surface for damage.
What is the difference between P0457 and P0455?
Both are EVAP leaks. P0457 is traced specifically to the fuel cap (loose or missing), while P0455 is a large EVAP leak that may be the cap but can also be a cracked hose or a stuck vent valve. P0456 is a small EVAP leak. All three start with checking the cap.