Investigating P0456 on Your 2022 Silverado
Your 2022 Silverado (T1XX platform) has flagged P0456—a very small EVAP leak. With the 2.7L turbo, 5.3L V8, 6.2L V8, or 3.0L Duramax diesel, GM's EVAP system is shared across all powertrains. The traditional threaded gas cap and the vent valve solenoid near the spare tire are the two primary suspects. Check your warranty status before spending money.
Evidence
- Steady check engine light
- P0456 on OBD-II scanner
- No towing or drivability issues
- Truck runs perfectly
- Gas cap may feel loose or worn
Causes Ranked
- Gas Cap Seal (High Likelihood): Worn seal or loose cap after 3–4 years of use. Tighten or replace for $10–$15.
- Vent Valve Solenoid (High Likelihood): Near the spare tire. GM's #1 EVAP failure point with well-known TSBs. $80–$220 installed.
- Purge Solenoid (Medium Likelihood): In the engine bay. Age-related wear. $80–$200.
- EVAP Hose (Medium Likelihood): Worksite vibration and towing stress. $100–$250.
- Fuel Tank Pressure Sensor (Low Likelihood): Degraded sensitivity. $120–$280.
Diagnostic Steps
- Remove, inspect, and reseat the gas cap—check the rubber seal for cracks
- Clear the code and drive a full cycle (50+ mixed miles)
- If code returns, inspect the vent valve solenoid near the spare tire
- Smoke test to locate the micro-leak
- Check for GM TSBs on the T1XX EVAP system
Costs
- Gas cap: $10–$15
- Vent valve solenoid: $80–$220
- Purge solenoid: $80–$200
- EVAP hose: $100–$250
- FTP sensor: $120–$280
- Smoke test: $80–$150
Can I Tow and Haul?
Yes. P0456 has zero impact on towing capacity, payload, engine performance, or any truck function. Safe to tow and haul normally.
Warranty Check
GM's 3yr/36k warranty runs through 2025 for a 2022 Silverado—check your mileage. Federal emissions (8yr/80k) covers EVAP through 2030. The vent valve solenoid is a well-known GM issue, so dealers are experienced with this repair.