Skip to main content

P0446: Evaporative Emission Control System Vent Control Circuit Malfunction

  • written by
    This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.
    edited by
    Director, Editorial Content
    Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

What does the P0446 error code mean?

The P0446 error code signifies a problem with the evaporative emission control (EVAP) system's vent control circuit. This system is responsible for capturing fuel vapors from the fuel tank and sending them to the engine to be burned rather than released into the atmosphere. The P0446 code is triggered when the vehicle's onboard computer (ECU) detects an incorrect voltage or resistance in the vent control valve circuit, indicating a malfunction in the vent control part of the EVAP system.

Why is the P0446 issue important?

It's important to address a P0446 error code due to its environmental and fuel efficiency implications. The EVAP system is designed to prevent harmful hydrocarbon emissions from escaping into the atmosphere, contributing to air pollution. A malfunction in this system can lead to increased emissions and a slight decrease in fuel efficiency because the fuel vapors are not being properly recycled back into the engine.

Can I safely drive my car with this error code?

While a vehicle with the P0446 error code is typically safe to drive in the short term, it's advisable to address the issue promptly. Ignoring this error can lead to a decline in fuel efficiency and, more critically, contribute to pollution. Additionally, driving with an unresolved P0446 can eventually lead to more significant problems with the EVAP or fuel system components and potentially result in costly repairs.

Common symptoms associated with the P0446 error code

  • Check engine light is illuminated on the dashboard
  • Fuel odor due to vapors escaping the EVAP system
  • Difficulty filling the gas tank (pump shuts off prematurely)
  • Decreased fuel efficiency

Diagnosing the P0446 error code

A mechanic typically starts with a visual inspection of the EVAP system, looking for signs of damage to the hoses or vent control valve. A scan tool is then used to check the ECU for any stored error codes that could provide further insight. Advanced diagnostic procedures may include checking the electrical resistance of the vent control valve and performing a smoke test to locate leaks in the EVAP system.

Repairing the P0446 error code

Common repairs include:

  • Replacing a faulty vent control valve
  • Repairing or replacing damaged EVAP hoses or connections
  • Clearing blockages in the vent control pathway
  • Fixing any related electrical issues, such as frayed wiring or poor connections

Prompt and accurate diagnosis is crucial to effectively address the P0446 error. Resolving the issue will restore the vehicle's environmental performance and ensure it runs efficiently.

Edmunds.comby

This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.

Steven Ewingedited by

Steven Ewing has worked in the automotive industry since 2003. In that time, he's written thousands of car-related articles and tested just as many vehicles. Steven is Edmunds' director of editorial content and has previously been on staff at Winding Road magazine, Autoblog, Motor1.com, CNET Roadshow, and was the U.S. correspondent for Top Gear magazine. Steven has also contributed to Automobile magazine, Ars Technica, Car and Driver, The Drive, Jalopnik, SlashGear, and dozens of other publications. In his spare time, Steven loves to play the drums, cook, and lust over small JDM cars that never made it to the States.

SPONSORED CONTENT 

2025 Acura MDX

SPONSORED CONTENT 

2025 Acura MDX

2025 Acura MDX

This is the 2025 Acura MDX. Unmatched performance and available Super Handling All-Wheel Drive™.
Full details, review, and specs
Learn More
Acura.com