P0455 on a 2015 Dodge Dart
P0455 means the EVAP system failed a leak check badly enough that the computer sees a large leak or no pressure/vacuum change.
Not your vehicle? See general P0455 info.
Most common causes on the 2015 Dodge Dart
Ranked from 510 NHTSA owner complaints filed for this vehicle.
- 1
Loose, missing, or damaged gas cap
Low severityThe classic large-leak trigger; complaints of a fuel-cap-linked check-engine light on this exact vehicle support checking the cap and its seal first.
Reported in 1 NHTSA complaintParts:fuel cap - 2
Restricted or stuck EVAP vent path (won't accept fuel normally)
Medium severityA vehicle that clicks off the pump nozzle almost immediately is showing a large pressure/venting abnormality consistent with a major EVAP-side restriction.
Reported in 1 NHTSA complaintParts:EVAP vent valve - 3
Disconnected or badly split EVAP hose
High severityA hose that has popped off a fitting or split open creates a leak large enough to fail the large-leak threshold.
Common cause - 4
Cracked fuel tank or filler neck
High severityA larger crack in the tank or filler neck area is a common gross-leak source.
Common cause - 5
Purge or vent valve stuck fully open
Medium severityA valve failing wide open (rather than just seeping) produces a large-leak-size failure.
Common cause - 6
Cracked charcoal canister
Medium severityA cracked canister housing is a common source of a leak large enough to affect the large-leak monitor.
Common causeParts:charcoal canister
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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0455 on your car still needs shop confirmation before any repair.
Common symptoms
- Check engine light
- Fuel smell
- Usually no performance issue
- Failed emissions readiness
What to check before replacing parts
Check the gas cap first
Look for: A loose, missing, or cross-threaded cap is by far the most common cause of a large EVAP leak code — if it doesn't click to full tightness or the seal is cracked, that's very likely the whole fault.
Inspect visible EVAP hoses
Look for: A large leak is often obvious: a hose disconnected at a fitting, split open, or chewed through (rodent damage is common) rather than a hairline crack.
Command the purge and vent valves with a scan tool
Look for: A valve that doesn't respond at all when commanded open/closed, or stays open when it should seal, prevents the system from holding pressure/vacuum and reads as a large leak.
Smoke-test the system
Look for: With a large leak, expect an obvious plume of smoke or a clearly audible hiss at the fault location — it should be easy to spot compared to a small-leak diagnosis.
Inspect the canister and filler neck
Look for: A cracked charcoal canister housing or a corroded/rusted-through filler neck (common on older vehicles) can leak enough to prevent the system from ever holding vacuum.
Rather have a pro handle it? Find a vetted local mechanic.