Fix P0446 Code: Evaporative Emission Control System Vent Control Circuit Malfunction

Fix P0446 Code: Evaporative Emission Control System Vent Control Circuit Malfunction

P0446 stands for “Evaporative Emission Control System Vent Control Circuit Malfunction.” In simpler terms, it means your car’s computer has detected an issue with the system that prevents fuel vapors from escaping into the atmosphere.

How Serious Is This Issue?

While P0446 isn’t an immediate threat to your engine, it’s still a serious issue. It can lead to increased emissions, failed emissions tests, and potentially damage other components if left unchecked.

Is It Safe to Drive with This DTC Code?

You can drive short distances with a P0446 code, but it’s not recommended for long trips. The issue could worsen over time, potentially leading to more expensive repairs or even fuel leaks.

Symptoms and Common Causes of P0446


  • Illuminated Check Engine Light
  • Difficulty refueling (gas pump may shut off repeatedly)
  • Slight decrease in fuel efficiency
  • Occasional fuel odor

Common Causes:

  • Faulty or loose gas cap
  • Damaged or clogged vent valve
  • Faulty vent control solenoid
  • Wiring issues in the vent control circuit
  • Damaged charcoal canister
  • Clogged or damaged vent hoses

How Can I Fix It?

  1. Check the gas cap: Ensure it’s tight and not damaged.
  2. Inspect the vent valve: Look for clogs or damage.
  3. Check wiring: Look for corroded or damaged wires in the vent control circuit.
  4. Inspect the charcoal canister: Check for damage or clogs.
  5. Examine vent hoses: Look for cracks, kinks, or blockages.

Can I Fix This DTC Code Myself?

Some fixes, like replacing a gas cap or inspecting visible components, are DIY-friendly. However, diagnosing electrical issues or replacing internal components might require professional help.

What Parts Might Need Replacement and How Much Will the Repair Cost?

  • Gas cap: $5-$50
  • Vent valve: $50-$200
  • Vent control solenoid: $70-$300
  • Charcoal canister: $200-$600
  • Wiring repairs: $50-$200

Labor costs can range from $50-$150 per hour, depending on your location and the shop.

Will the Repair Be Expensive?

The cost can vary widely depending on the root cause. Simple fixes like a new gas cap are inexpensive, while replacing a charcoal canister can be pricier.

Can I Reset the DTC Code Myself?

Yes, you can reset the code using an OBD-II scanner. However, if you haven’t fixed the underlying issue, the code will likely return.

Will It Affect Performance or Fuel Efficiency?

You might notice a slight decrease in fuel efficiency. Performance usually isn’t noticeably affected, but ignoring the issue could lead to more significant problems over time.

How Can I Prevent It in the Future?

  • Regularly inspect your gas cap and replace it if damaged.
  • Follow your vehicle’s maintenance schedule.
  • Address any fuel or emissions-related issues promptly.
  • Use quality fuel and avoid overfilling your tank.

Remember, taking care of this issue promptly can save you money and headaches in the long run. If you’re not comfortable diagnosing or repairing it yourself, don’t hesitate to consult a professional mechanic. Your car (and the environment) will thank you!

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