P0456 means the Charger failed a very-small EVAP leak check; it does not name the gas cap. Record fuel level and filler condition, verify purge and ESIM/vent sealing, then use EVAP-safe smoke to inspect rear underbody lines, canister and tank seals. FCA bulletin 18-084-16 includes P0456 for specified 2013–2015 LD Charger 5.7L applications, but software is only a branch after physical testing and exact VIN/calibration confirmation.
Match the symptom
Select the closest observation. The result changes the first test; it does not name a part to replace.
Record cap or filler condition before changing it.
What can set P0456—and how to separate it
The order below is evidence-driven, not a universal probability ranking. Vehicle year, repair history, companion codes and the operating condition in freeze frame change where diagnosis should begin.
| Possible cause | Evidence that supports it | First useful test |
|---|---|---|
| Cap/filler seal or closure fault | Found condition or sealing test fails | Cap/filler inspection |
| Purge valve leaks when closed | Manifold vacuum passes with purge off | Closed-state sealing test |
| ESIM/vent, hose or canister small leak | Leak verification or regulated smoke localizes | wiTECH leak test and smoke |
| Tank or pump-module seal leak | Recent service or top-of-tank smoke | Sectional EVAP test |
| PCM calibration branch | Exact platform, engine, VIN and software match | Bulletin/applicability check |
Keep the filler untouched until it is documented
A well-meaning cap tightening can erase the found condition without proving that the cap was responsible. Photograph the seal and tether area, note whether the cap was seated, and preserve fuel level and ambient temperature before clearing anything.
The Charger’s low rear body puts canister plumbing and vapor lines near road debris and lift points. Inspect clips, abrasion and repairs around the tank before assuming that a small-leak monitor failure is an electronic problem.
Purge and ESIM require different proof
A purge solenoid can click and still pass manifold vacuum while commanded closed. Test actual sealing, because unintended purge flow can also explain a difficult restart immediately after refueling or an unexpected fuel-trim change.
The leak-detection switch and vent path must move and seal as designed. Use wiTECH functional testing where available, then section the system with regulated smoke rather than feeding unrestricted shop air into vapor components.
The 5.7L bulletin has hard boundaries
Bulletin 18-084-16 identifies LD Charger, the 5.7L EZC/EZH sales codes and particular model years. A 3.6L Charger or a vehicle outside the calibration range does not qualify merely because P0456 appears.
Even on an eligible car, record the current software level and complete the manufacturer prechecks. A verified hose, filler or valve leak remains a physical repair; the flash branch addresses only the software behavior described by the bulletin.
Save these scan-data clues
Freeze frame is a snapshot of conditions when the PCM matured the fault. It can distinguish an idle-only problem from a load, cold-start or monitor-completion problem. Clearing first throws that context away.
- Exact VIN, platform, model year and engine sales code
- All confirmed, pending and permanent companion codes
- RPM, load, coolant temperature and vehicle speed
- Relevant commanded and actual scan data
- Recent service, repairs and symptom conditions
- Manufacturer bulletin and current software/VIN status
A practical diagnostic workflow
- 01Identify platform and engine
Component layout and software branches differ.
- 02Preserve refueling evidence
Do not tighten or clear before recording.
- 03Run leak verification
Use wiTECH function tests where supported.
- 04Test purge and vent sealing
A click does not prove closure.
- 05Smoke at EVAP-safe pressure
Section filler, canister, hoses and tank.
- 06Verify monitor
Meet fuel-level and soak conditions after repair.
Do not replace the most commonly named component from P0456 alone. Confirm the exact engine, preserve evidence and complete the manufacturer test sequence before ordering parts.
Why the model year changes the test
Modern Charger diagnostics span LX and LD rear-wheel-drive platforms, optional AWD and 2.7L, 3.5L, 3.6L Pentastar, 5.7L HEMI, 6.1L and 6.4L engines. Cylinder banks, oil-pressure control, cam sensing, EVAP plumbing and catalyst locations are not interchangeable. Confirm model year, VIN, engine sales code, build date and current PCM calibration before applying any test value, bulletin or diagram.
- 18-084-16 is limited to specified 2013–2015 LD Charger 5.7L applications.
- V6 and HEMI purge plumbing and calibrations differ.
- Rear-impact or fuel-pump service history raises underbody and tank-seal priority.
- A software update cannot seal a cracked hose or leaking valve.
P0456 FAQ
Is it always the gas cap?+
No. Purge, ESIM/vent, hoses, canister and tank seals can cause it.
Can I drive?+
Usually briefly without odor or wet fuel.
Can purge leakage cause it?+
Yes, if the valve does not seal when commanded closed.
Can I use shop air?+
Not unregulated; EVAP pressure must be limited.
Why did a new cap not help?+
The leak or open valve may be elsewhere.
Does every vehicle need a PCM flash?+
No. Platform, engine, VIN and calibration must match a bulletin.
Why is readiness incomplete?+
Fuel level, soak and temperature gate the monitor.
What confirms repair?+
A passing leak test and completed EVAP monitor.
Ford diagnostic references
These documents explain Ford monitor operation. Exact pinpoint tests, connector views and specifications must be selected for the truck's VIN and model year in current service information.
01FCA Bulletin 18-084-16 — 2013–2015 Charger 5.7L PCM updateApplies to specified LD Charger 5.7L applications and includes P0456 and P0300 among listed diagnostic improvements↗02Stellantis/Mopar service informationFactory VIN-, platform-, engine-sales-code and calibration-specific service information↗03Mopar vehicle informationOfficial owner manuals and model-year warning, fluid, engine and operating information↗