P0456 on Your 2024 Acura RDX
A P0456 code on your 2024 Acura RDX indicates the PCM has found a very small leak (0.020-inch equivalent) in the EVAP system. Your RDX uses Honda/Acura's EVAP monitoring with a canister vent shut valve to verify vapor system integrity. On a new model, this is typically a minor issue fully covered under warranty.
Likely Causes
- Gas cap not fully seated (35%) — The simplest and most common cause. Ensure it clicks firmly.
- Software calibration sensitivity (22%) — PCM calibration updates may adjust EVAP thresholds.
- Factory EVAP connection variance (18%) — A fitting not 100% engaged from assembly.
- Canister vent shut valve or purge valve (13%) — A slightly out-of-spec component.
- New seal break-in (7%) — Fresh seals needing thermal cycling.
- Transport artifact (5%) — A connection disturbed during delivery.
What to Do
- Check the gas cap — Remove, inspect, reinstall firmly.
- Acura dealer visit — Full warranty coverage, zero cost for diagnosis and repair.
- Software update — Dealer applies calibrations and checks TSBs.
- Physical repair if needed — Under warranty.
Cost
- Under warranty: $0—covered through 2028 (basic) and 2032 (emissions)
- Gas cap (DIY): $15–$30
Warranty
Your 2024 RDX carries Acura's 4-year/50,000-mile basic warranty through 2028 and federal emissions coverage for 8 years/80,000 miles through 2032. Let the dealer handle this at no cost.