P0456 on Your 2024 Audi A4
A P0456 code on your 2024 Audi A4 indicates the ECM has found a very small leak (0.020-inch equivalent) in the EVAP system. The A4 uses the VW Group's EVAP architecture with a Leak Detection Pump (LDP) and N80 purge valve. On a new model, this is typically minor and fully covered by Audi's comprehensive warranty.
Your 2024 A4's 2.0L TFSI turbocharged engine shares its EVAP platform with other VW/Audi vehicles, meaning the diagnostic approach is well-established even on newer models.
Likely Causes
- Gas cap not fully seated (33%) — The most common cause. Ensure it's tightened firmly.
- Software calibration sensitivity (22%) — Audi may have ECM calibration updates that adjust EVAP monitor thresholds.
- Factory EVAP connection variance (18%) — A quick-connect fitting not fully engaged from assembly.
- N80 purge valve irregularity (15%) — A slightly out-of-spec N80 valve, though less common on new vehicles.
- LDP variance (7%) — The Leak Detection Pump may have a marginal reading.
- New seal break-in (5%) — Fresh seals needing thermal cycling.
What to Do
- Check the gas cap — Remove, inspect, reinstall firmly.
- Audi dealer visit — Full warranty coverage means zero cost. ODIS diagnostics and TSB checks included.
- Software update — Dealer applies any pending ECM calibrations.
- Physical repair if needed — Smoke test and component replacement under warranty.
Cost
- Under warranty: $0—covered under 4-year/50,000-mile Audi warranty through 2028
- Gas cap (DIY): $15–$35
Warranty
Your 2024 A4 carries Audi's 4-year/50,000-mile basic warranty through 2028 and the federal emissions warranty for 8 years/80,000 miles through 2032. Let the dealer handle this at no cost.