P0446 code

Where would you guys start?

 

First - I would check gas cap for proper tightness i.e. tighten until it clicks a couple of times; remove positive battery terminal for 30 sec and replace for ECM reset. If that doesn't work then go to next item as listed below. Good luck!



Code P0446 Definition
Evaporative Emission Control System Vent Control Circuit Malfunction

What Does P0446 Mean?
The evaporative emission control (EVAP) system prevents fuel vapors from escaping into the atmosphere. The fuel vapors from the fuel tank are absorbed and stored by charcoal pellets in the charcoal canister. The vent control valve is controlled by the engine control module (ECM) and allows air to flow into the charcoal canister to purge the gas vapors into the engine air intake to be burned. The flow of the gas vapors from the charcoal canister to the engine air intake is controlled by a purge valve. Both the vent control valve and the purge valve are usually open when the engine is at normal operating temperature. However, the ECM occasionally performs leak tests to ensure the evaporative emission control system is working properly. During the leak test, the ECM closes the vent control valve and purge valve to create a vacuum. When P0446 is triggered, the ECM has detected a short in the circuitry to activate the vent control valve, or the EVAP system failed to maintain the vacuum during the active EVAP leakdown test.

P0446 Symptoms

• Check Engine Light is on
• Slight decrease in fuel economy
• Gasoline smell

P0446 Causes

• Missing fuel cap
• Defective Evaporative Vent Valve
• Defective or damaged fuel cap
• Distorted, damaged or cracked Fuel Tank Filler Neck
• Torn or punctured Evaporative system hose(s)
• Defective Fuel Tank Sending Unit gasket or seal
• Split or damaged Carbon Canister
• Defective or damaged fuel tank
  
  

 

That’s as helpful of a post as you will ever get for this problem.

 

Just wondering if it’s one of those problems with 20 possible causes but in practice everyone knows it’s really just one of them 90% of the time.

 

I did a search and it seems like the gas cap is the most common. I'd start with that.

 

Yup... Happened to my wife after she filled her 4-Runner tank.

A quick wife lesson for always securing the gas cap eliminated future failures.

I typically keep her tank topped off and in all fairness, she was not aware.

 

My truck was the gas cap on my girlfriends Camry I found a vacuum line removed from the switch canister on the fender.