Investigating P0442 on Your 2021 Hyundai Sonata
A P0442 code on your 2021 Hyundai Sonata means the engine control module has found a small leak in the evaporative emission control system. This system captures fuel vapors from the gas tank and routes them to the engine for combustion. P0442 flags a leak roughly 0.020 inches in diameter.
The 2021 Sonata is the second year of the eighth generation on Hyundai's N3 platform, available with a 2.5L four-cylinder, 1.6L turbo, or 2.5L turbo (N Line). Hyundai's EVAP system uses the PCSV, CCV, and FTPS. After a few years of use, minor component wear is possible.
Probable Causes
- Gas Cap Wear or Poor Seating — After a few years, the gas cap O-ring can develop minor wear. Cross-threading is also common. Check and replace if needed ($10–$20).
- PCSV (Purge Control Solenoid Valve) Issue — Engine heat cycling degrades the PCSV over time, particularly on turbocharged variants with higher underhood temperatures.
- CCV (Canister Close Valve) Problem — Moisture and debris can affect the CCV's sealing ability.
- Vapor Line Looseness — Quick-connect fittings can develop slight looseness from vibration.
- FTPS Drift — The Fuel Tank Pressure Sensor may drift slightly, causing false readings.
Warranty Advantage
- Check the gas cap — Free first step. Remove, inspect, reinstall firmly.
- Visit your Hyundai dealer — Your 2021 Sonata is within Hyundai's 5-year/60,000-mile basic warranty (through approximately 2026). EVAP components are covered for 8 years or 80,000 miles. Repairs should be at no cost.
- GDS diagnosis — The dealer's GDS system provides comprehensive EVAP active testing.
Costs if Out of Warranty
Gas cap $10–$20, PCSV $130–$270, CCV $100–$240, FTPS $90–$200.