The P0455 code on a Dodge means the EVAP system found a large leak — it tried to seal the fuel-vapor system and couldn’t build any vacuum at all. P0457 is its more specific sibling: a leak pattern that looks exactly like a loose or missing gas cap, usually right after a fill-up. The good news: these are among the cheapest codes in the book. Check the cap first — click it tight (or seat the capless funnel flap on Chargers and Challengers), and the light often turns itself off within a few days of driving. No cap problem? Then look for a disconnected hose or a failed ESIM.
What Do P0455 and P0457 Mean on a Dodge?
Your Dodge’s EVAP system traps fuel-tank vapors in a charcoal canister instead of letting them escape, then burns them in the engine later. For that to work the whole network — tank, filler neck, cap, hoses, canister, valves — must hold a seal. The PCM tests that seal regularly (on most 2007+ Dodges via the ESIM switch on the canister), and stores a code sized to what it finds:
- P0455 — Evaporative Emission System Leak Detected (large leak): the system couldn’t hold vacuum at all. Think missing cap, disconnected hose, cracked canister.
- P0457 — Leak Detected (fuel cap loose/off): the leak signature matches an unsealed filler — classically set on the first drive after refueling.
- Their small sibling P0456 (very small leak, pinhole class) gets its own diagnosis path — covered in our Dodge P0456 guide.
Size matters because it changes where you look: a large leak is rarely subtle. You’re not hunting a pinhole with a smoke machine — you’re looking for something obviously open: a cap left on the pump roof, a vapor hose knocked off during another repair, a vent valve stuck wide open.
Dodge P0455 / P0457 Symptoms
- Check engine light — steady, with the engine running completely normally
- Fuel smell — more likely than with small-leak codes, especially near the rear of the vehicle or after parking in the sun
- Slightly worse fuel economy — escaping vapor is wasted gasoline
- The light appears right after a fill-up — the classic P0457 calling card
- Failed emissions inspection — both the stored code and the incomplete EVAP monitor are automatic fails
Common Causes of P0455 and P0457 on a Dodge
In rough order of how often they turn out to be the culprit:
- A loose, missing, or worn-out gas cap — the cause in a huge share of cases. Not clicked tight, cross-threaded, left at the pump, or sealing with a rubber gasket that’s cracked with age.
- Capless filler problems (Charger and Challenger, roughly 2011+) — these models have no cap at all; a spring-loaded flapper seals the filler. Debris holding the flapper open, a deformed seal, or repeated use of the wrong nozzle/funnel sets large-leak codes. The fix is cleaning or replacing the capless filler housing.
- A vapor hose knocked off or split — frequently right after unrelated work (exhaust, suspension, fuel pump); also rodent damage and age-cracked rubber near the canister at the rear.
- A failed ESIM or vent valve stuck open — if the system’s own test hardware can’t close the circuit, every test reads “large leak.”
- A cracked charcoal canister — road debris and corrosion, especially on trucks; often paired with a fuel smell.
- A rusted or damaged filler neck — the cap is fine but the metal it seals against isn’t; common on older RAMs and Dakotas in salt states.
- A leaking fuel-tank seal or sender O-ring — less common; usually found after a recent fuel-pump job.
Cause → Symptom → Fix at a Glance
| Cause | Typical symptom | Fix |
|---|---|---|
| Loose/missing/worn gas cap | Light right after refueling; P0457 stored; cap seal cracked | Click tight or replace the cap (OEM-quality) |
| Capless filler fault (Charger/Challenger) | Large-leak codes on a capless car; flapper visibly stuck or dirty | Clean or replace the capless filler housing |
| Disconnected/split vapor hose | Code appears after other repairs; hose visibly off at the canister | Reconnect or replace the hose |
| ESIM / vent valve stuck open | No physical leak found; codes persist after cap and hose checks | Replace the ESIM or vent valve |
| Cracked canister | Fuel smell at the rear; visible damage underneath | Replace the canister assembly |
| Rusted filler neck | New cap doesn’t help; rust where the cap seats | Replace the filler neck |
How to Diagnose P0455 / P0457 on a Dodge Step by Step
Cheap and obvious first — this code family rewards it:
- Open the fuel door and look. Is the cap there? Tight? Remove it, inspect the rubber seal for cracks, wipe the filler-neck lip, and reinstall until it clicks firmly. On a capless Charger/Challenger, shine a light into the filler: the flapper should sit closed and clean — gently clear any debris around its seal.
- Clear the code (or just drive). If the cap was the issue, the light goes out by itself after roughly three successful EVAP monitor runs — typically a few days of normal driving. A scanner clears it immediately; either way, if it stays gone, you’re done.
- Think about recent work. Exhaust, suspension, fuel-pump, or hitch jobs near the tank are prime suspects for a vapor hose left off. Check the lines at the canister (near the tank) and the purge line up front.
- Look and smell underneath. A large leak often announces itself: a hanging hose, a cracked canister, a fuel smell at the rear. No smoke machine needed for most P0455s.
- Test the vent side. If everything looks sealed, a vent valve or ESIM stuck open is the remaining common cause — a capable scanner can command the vent closed and watch whether the system will finally hold vacuum.
- Escalate to a smoke test only if the leak hides. Persistent large-leak codes with nothing visible justify a shop smoke test ($75–$150) — it will show a big leak instantly.
Dodge P0455 / P0457 Repair Cost
Typical US shop prices (parts + labor) by root cause:
DIY note: this is the friendliest code family in OBD2 — checking the cap costs nothing, vapor hoses at the canister are visible from under the car, and even the ESIM is a simple clip-in part on most models. Skip “EVAP system cleaner” products; leaks are mechanical, not dirty.
Is It Safe to Drive a Dodge with P0455 or P0457?
These are emissions-sealing faults; they don’t affect how the car runs or its reliability. Fix within a few weeks, mainly for fuel smell, wasted vapor, and emissions inspections.
A persistent gasoline odor — not just a whiff after filling up — means liquid fuel or heavy vapor is escaping somewhere. Get it inspected promptly rather than driving on it for weeks, and don’t park a strongly fuel-smelling vehicle in an enclosed garage.
How to Reset P0455 / P0457 After the Fix
- Fix the seal first — cap, hose, valve, whatever the diagnosis found. Clearing the code without a fix just schedules the light’s return.
- Clear with a scanner or let it self-clear. After about three consecutive successful EVAP monitor runs the light turns off on its own; the monitor wants a cold start, gentle driving, and a fuel level roughly between a quarter and three-quarters of a tank.
- Plan for inspections. The EVAP monitor is slow — do the repair and the driving well before an emissions test so readiness completes in time.
The full clearing and drive-cycle procedure is covered in our Dodge check engine light reset guide.
FAQ: Dodge P0455 and P0457 Codes
Can a loose gas cap really cause a P0455 or P0457 code on a Dodge?
Yes — it is the most common cause for both codes. P0457 is literally defined as a leak consistent with a loose or missing fuel cap, and a cap that isn’t clicked tight can also register as the generic large leak, P0455. Tighten the cap until it clicks, inspect its rubber seal for cracks, and drive normally for a few days; if the cap was the problem, the light turns itself off after about three successful EVAP monitor runs.
What is the difference between P0455, P0456, and P0457 on a Dodge?
They are all EVAP leak codes sized by severity. P0455 is a large leak — the system cannot hold vacuum at all, pointing at a missing cap, a disconnected hose, or a stuck-open vent. P0456 is a very small leak, as fine as 0.02 inches, which usually needs a smoke test to find. P0457 is a leak that matches the specific signature of a loose or open fuel cap. Large leaks are usually found by eye; small leaks by smoke machine.
My Charger has no gas cap — how do I get a P0455 code?
Capless Dodge Chargers and Challengers seal the filler with a spring-loaded flapper instead of a cap. Debris caught around the flapper, a worn flapper seal, or damage from improper nozzles or funnels lets the system leak, producing the same large-leak codes a loose cap would. Shine a light into the filler and check that the flapper sits fully closed and clean; cleaning around the seal or replacing the capless filler housing is the fix.
Is it safe to drive my Dodge with a P0455 or P0457 code?
Yes. These are emissions-sealing faults — the engine runs normally and nothing mechanical is at risk. The practical concerns are wasted fuel vapor, a possible gasoline smell, and a guaranteed emissions-inspection failure while the code is stored. Fix it within a few weeks, and treat a strong persistent fuel smell as a reason to move faster.
How much does it cost to fix P0455 or P0457 on a Dodge?
Often nothing: tightening the gas cap is free and resolves a large share of cases. A replacement cap is $10–$40, reconnecting or replacing a vapor hose $0–$200, and an ESIM, vent valve, or capless filler housing typically $100–$300 installed. The expensive outcomes — a charcoal canister or rusted filler neck at $200–$600+ — are exactly why you confirm the leak visually or with a $75–$150 smoke test before buying parts.
Chasing a smaller, sneakier leak instead? The Dodge P0456 small-leak guide covers the pinhole-class diagnosis. EVAP complaints are also minivan-and-truck classics — see the Grand Caravan guide.