P0456 on Your 2022 Infiniti QX80
A P0456 code on your 2022 Infiniti QX80 means the ECM has detected a very small leak—approximately 0.020 inches—in the EVAP system. The body-on-frame QX80, powered by a 5.6L V8, uses Nissan/Infiniti's EVAP monitoring system. The QX80's robust construction and large fuel tank create specific considerations for EVAP diagnosis.
Common Causes
- Gas cap seal wear (30%) — Three years degrades the seal. The QX80's large fuel tank generates significant vapor pressure.
- Purge volume control valve seepage (23%) — Nissan/Infiniti's purge valve can develop internal leaks.
- EVAP line looseness (18%) — The body-on-frame design creates vibration that loosens connections.
- Canister vent control valve issue (14%) — The vent valve may develop wear.
- Charcoal canister damage (10%) — The QX80's underbody exposure to road debris.
- Fuel tank seal (5%) — Slow gasket degradation on the large fuel tank.
Diagnostic Steps
- Gas cap test — New OEM cap ($15–$35), clear code, drive for a week.
- Visual inspection — Check EVAP hoses and connections, particularly along the frame.
- Smoke test — Professional testing pinpoints the leak.
- CONSULT diagnostics — Infiniti's dealer tool monitors EVAP data.
- Component testing — Individual valve testing.
Repair Costs
- Gas cap: $15–$35 (DIY)
- Purge volume control valve: $160–$350
- Canister vent control valve: $170–$360
- EVAP hose repair: $100–$260
- Charcoal canister: $290–$560
Warranty Coverage
Your 2022 QX80 is covered under Infiniti's 4-year/60,000-mile basic warranty through 2026 and the federal emissions warranty for 8 years/80,000 miles through 2030.