Following the P0446 Trail on Your 2020 Nissan Altima
A P0446 code on your 2020 Altima indicates the ECM has found an electrical malfunction in the EVAP vent control circuit. On Nissan vehicles, the canister close valve is at the center of this investigation—it's not responding within expected electrical parameters. This is a circuit fault requiring electrical diagnosis.
The 2020 Altima is part of the sixth generation (L34) with the 2.5L QR25DE or available 2.0L VC-Turbo engine. After five years of service, the canister close valve and its wiring are the most likely sources of this circuit malfunction.
Clues at the Scene
- Check engine light on with P0446 stored
- Difficulty at the fuel pump—nozzle shutting off
- EVAP readiness monitor won't complete
- Possible faint fuel odor near the rear
- No drivability issues with either engine option
Suspect Lineup
Five years of ownership data confirms these ranked causes:
- Canister Close Valve Failure (High Likelihood): The leading P0446 cause on Nissan sedans. After five years, the valve's coil can degrade or the valve can stick mechanically. Parts: $50–$95, labor: $80–$150.
- Corroded Wiring or Connector (High Likelihood): Road moisture and temperature cycling corrode the canister close valve's electrical connections. Repair: $75–$200.
- Charcoal Canister Saturation (Medium Likelihood): Years of fuel overfilling degrade canister capacity, affecting vent circuit operation. Replacement: $130–$280.
- Leak Detection Pump Malfunction (Medium Likelihood): Nissan's unique leak detection pump can affect EVAP system behavior if it fails. Replacement: $150–$300.
- Ground Circuit Corrosion (Low Likelihood): A corroded ground connection in the canister close valve circuit creates resistance and intermittent faults. Cleaning: $50–$100.
Diagnostic Approach
Confirm P0446 with an OBD-II scan. Locate the canister close valve near the charcoal canister at the rear of the Altima. Disconnect the connector and inspect for corrosion. Test valve resistance with a multimeter and apply 12V to verify actuation. Nissan's CONSULT system provides enhanced diagnostics, but most testing can be done with basic tools.
Warranty Status
Your 2020 Altima is past Nissan's 3-year/36,000-mile bumper-to-bumper warranty. The federal emissions warranty of 8 years/80,000 miles covers EVAP components through 2028. If your Altima has fewer than 80,000 miles, contact a Nissan dealer for a potential free repair.
Case Resolved
The P0446 on your 2020 Altima is a manageable repair. The canister close valve is the most common fix and an affordable repair if warranty has lapsed. Check the emissions warranty window—you may still qualify for free coverage. Your sedan's fuel economy and daily driving comfort aren't affected by this code.