Understanding P0456 on Your 2022 Acura RDX
A P0456 code on your 2022 Acura RDX means the PCM has detected a very small leak—about 0.020 inches—in the EVAP system. The third-generation RDX (2019+) is Acura's best-selling model, powered by a 2.0L turbocharged four-cylinder and using Honda/Acura's EVAP monitoring system with a canister vent shut valve.
At three-plus years old, your RDX is beginning to enter the window where EVAP component wear can trigger codes, though simpler causes like gas cap issues remain the most likely explanation.
Common Causes
- Gas cap seal wear (33%) — Three years of fueling degrades the rubber seal. Always check first.
- Canister vent shut valve malfunction (23%) — Honda/Acura's vent control valve can develop faults that prevent proper system sealing during monitor tests.
- Purge valve seepage (18%) — The purge solenoid may develop a slight internal leak.
- EVAP hose or connection looseness (14%) — Thermal cycling and vibration loosen connections over time.
- Charcoal canister issue (7%) — Road debris or moisture damage.
- Fuel tank seal (5%) — Slow gasket degradation.
Diagnostic Steps
- Gas cap test — New OEM cap ($15–$30), clear code, drive for a week.
- Visual inspection — Check EVAP hoses and connections for damage.
- Smoke test — Professional testing pinpoints the leak.
- i-HDS diagnostics — Acura dealer tool monitors EVAP pressure and valve operation.
- Component testing — Test canister vent shut valve and purge valve individually.
Repair Costs
- Gas cap: $15–$30 (DIY)
- Canister vent shut valve: $170–$360
- Purge valve: $140–$310
- EVAP hose repair: $90–$220
- Charcoal canister: $270–$500
Warranty Coverage
Your 2022 RDX is covered under Acura's 4-year/50,000-mile basic warranty through 2026. The federal emissions warranty extends to 8 years/80,000 miles through 2030. Verify eligibility with your dealer before paying out of pocket.