I recently bought a 2006 Toyota Corolla and after couple of days, I discovered that engine light is turned on. I immediately consulted with Toyota Service center and it was diagnosed with P0471 problem and they are asking me to replace the whole Transmission unit for $4000. The current car mileage is around 134,000 and now I'm in dilemma whether to spend that much money for transmission. Do anybody has any idea about any other alteranative option to fix the issue? Please, let me know.