P0446 2005 Toyota Prius -

Question

Few days ago, Check Engine light comes on and I rushed to take it to garage. Repairer told me to the problem cause by Emission Control System. He recommended me to change Charcoal Canister in order to fix the problem.

A day later, I went to Toyota Service and technician told me not to change anything as this is common problem happen to most Toyota model due to fuel quality (i live in rural area where there is no standard gas station like Total or Caltex,...). He added that if i change the Charcoal Canister and still using that kind of mixups gasoline, the new Charcoal Canister will be broken again. They just reset the code and let me go.

What should i do in this case and can i still drive my car without fixing it? Does it lead to serious problem in the future?

Please help!!!

Answer 1

P0446 Evaporative emission control system vent control circuit

The purpose of the CK ENG LT is to protect the catalytic convertor and the catalytic convertor is to protect the enviroment, There has to be another note on top of this and that , P0446 mean the evaporative system has detected raw fuel evaporating into the atmoshere. , This may not be a big deal , but imagine thousands and thousands of vehicle on the road emitting raw fuel in the atmophere. This is the purpose for the EVAP control system. The fix for this,  is a difficult one. that why alot of repair shop would tell you replace the charcol cansiter, with canister as a whole the EVAP pressure switch is included,the VSV is included. But majority of times  this is not the problem , even with a good EVAP smoke machine and a Toyota grade factory scan tool. it a hit and miss with the charcoal canister being replaced

Typical charcoal canisiter component.

When it comes to P0446 alot of the code cause was with the Vapor pressure valve.