What's Behind the P0456 on Your 2020 Dodge Challenger?
A P0456 code on your 2020 Dodge Challenger means the PCM has detected a very small leak in the EVAP system—about 0.020 inches. Your Challenger uses Stellantis's NVLD (Natural Vacuum Leak Detection) sensor to monitor the sealed fuel vapor system, and it's sensitive enough to detect the tiniest breach.
Whether you own the 3.6L Pentastar SXT, the 5.7L HEMI R/T, the 6.4L Scat Pack, or the legendary supercharged Hellcat, the EVAP system is identical across all trims. Rest easy—P0456 has absolutely no effect on your Challenger's performance.
Common Causes
- Gas cap seal deterioration (30%) — Five years of use wears the rubber seal. This is always the first clue in any EVAP leak investigation.
- NVLD sensor malfunction (22%) — The NVLD is the primary monitoring component in the Stellantis EVAP system. It can develop internal faults with age and mileage.
- EVAP line degradation (18%) — Heat from the engine bay (particularly on high-output HEMI models) and road vibration can crack or loosen vapor lines over five years.
- Purge valve seepage (15%) — The purge solenoid may develop a slight leak-through when commanded closed.
- Charcoal canister damage (10%) — Road debris impacts can compromise the underbody-mounted canister.
- Fuel tank or filler seal (5%) — Rubber seals at the filler neck and fuel pump module degrade with age.
Diagnostic Steps
- Gas cap replacement — Install a new OEM-spec cap ($15–$30), clear the code, and monitor for a week.
- Visual inspection — Check all accessible EVAP hoses and connections for cracks, loose fittings, or heat damage.
- Smoke test — A professional smoke test pinpoints the exact leak location by filling the system with visible smoke.
- wiTech NVLD check — Stellantis's diagnostic tool verifies NVLD sensor function in real time.
- Component-level testing — Test the purge valve and vent valve individually if the smoke test doesn't reveal an obvious source.
Repair Costs
- Gas cap: $15–$30 (DIY)
- NVLD sensor: $200–$400
- EVAP hose repair: $100–$250
- Purge valve: $150–$320
- Charcoal canister: $280–$550
Warranty and DIY Notes
Your 2020 Challenger's basic warranty has expired, but the federal emissions warranty covers EVAP components for 8 years/80,000 miles through 2028. Check your mileage—you may still qualify. DIY feasibility is moderate; the gas cap is simple, but NVLD sensor access and smoke testing may require professional tools.