Tracking P0446 on Your 2020 Chevrolet Colorado
A P0446 code on your 2020 Colorado reveals an electrical malfunction in the EVAP vent control circuit. The PCM determined the vent valve solenoid isn't operating as commanded—a circuit-level fault rather than a physical vapor leak. On GM's mid-size truck platform, this code has a well-established diagnostic path.
The 2020 Colorado is part of the second generation with engine options including the 2.5L four-cylinder, 3.6L V6, and 2.8L Duramax diesel. Like its full-size Silverado sibling, the Colorado positions the vent valve solenoid near the charcoal canister at the rear, where it faces road exposure from truck duties.
Symptoms You've Noticed
- Check engine light on with P0446 stored
- P0449 companion code may also appear
- Difficulty refueling—nozzle auto-shutoff at the pump
- Fuel vapor smell near the truck bed or spare tire
- No effect on engine power or truck capability
Suspects Under Investigation
Five years of real-world data confirms these ranked causes for the 2020 Colorado:
- Vent Valve Solenoid Failure (High Likelihood): The primary suspect on GM trucks. After five years of road exposure, the solenoid near the charcoal canister can develop coil failures or valve sticking. Parts: $30–$65, labor: $80–$150.
- Corroded Connector or Wiring (High Likelihood): Truck use—towing, off-road, work sites—accelerates wiring corrosion at the rear-mounted vent valve solenoid. Repair: $75–$220.
- Charcoal Canister Saturation (Medium Likelihood): Regular fuel overfilling degrades the canister over time. Replacement: $130–$290.
- Fuel Tank Pressure Sensor Issue (Medium Likelihood): The pressure sensor can drift after years of thermal cycling, confusing EVAP circuit monitoring. Replacement: $100–$220.
- Ground Circuit Corrosion (Low Likelihood): A corroded ground point in the vent solenoid circuit creates resistance and intermittent faults. Cleaning the ground: $50–$100.
Diagnostic Trail
Scan for P0446 and check for P0449. Locate the vent valve solenoid near the charcoal canister at the rear of the Colorado. Inspect the connector for moisture or corrosion. Test solenoid resistance and apply 12V to verify operation. The second-gen Colorado's solenoid location is accessible from under the truck bed with jack stands.
Warranty Status
Your 2020 Colorado is past GM's 3-year/36,000-mile bumper-to-bumper warranty but within the federal emissions warranty of 8 years/80,000 miles through 2028. If your truck has fewer than 80,000 miles, contact a Chevrolet dealer for a potential no-cost EVAP repair.
Closing the Case
The P0446 on your 2020 Colorado is a common mid-size truck code that doesn't compromise your towing, hauling, or off-road capability. The vent valve solenoid is the most frequent fix and an affordable repair. Check your emissions warranty before paying out of pocket—you may still be covered through 2028.