Diagnose and fix Camry P0440, P0441, P0446 trouble code
If you have a 1998-1999 Solara or Camry P0440, P0441, P0446 trouble code issue, Toyota has issued a service bulletin # EG013-02 to address this problem. The bulletin states that under some conditions, you may encounter a Solara or Camry P0440, P0441, P0446 trouble code.
The evaporative emissions system in Toyota vehicles operates like most other EVAP test systems. Fuel vapors are stored in the charcoal canister. After a fuel fill-up, the system opens the EVAP vacuum switching valve (VSV) in the engine compartment to suck gas vapors from the charcoal canister. In other vehicles this valve is often called the canister purge valve. Fresh filtered air enters the charcoal canister and the fuel vapors are sucked into the engine.
The second VSV valve is call the Vapor pressure Sensor VSV and it closes to the atmosphere so the vapor pressure sensor can measure fuel tank pressure/vacuum to detect and EVAP leak.
The problem is usually a bad VSV
The problem is due to an inoperative Vapor Pressure Sensor 3 way
Vacuum Switching Valve (VSV). Toyota has re-engineered the part #90910-12271 to solve the problem. You can conduct resistance and short to ground tests and apply vacuum from a hand held vacuum pump to determine if the valve is closing and holding properly, but the problem is so wide spread, you’re better off just replacing the valves.
To learn more about Evaporative Emissions Systems, read this post
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