Two problems related to catalytic convertor have been reported for the 2001 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2001 Toyota Prius based on all problems reported for the 2001 Prius.
Several times when the accelerator was pressed and the car slowed down the check engine light came on. Vehicle will drive normally for awhile, but problem seemed to occur at least once every 1-2 years. The last time, I spent $900 to replace an accelerator sensor. This time, the dealership stated I needed to replace the ecm, and the catalytic converter for a total charge of $3500. There were no generic catalytic converters, the one to be used was $1700. Also, had been several incidents where there had been issues following an oil change where the dealer said that oil was where it shouldn't be.
I own a 2001 Prius since March of 2006. It ran fine for one year, but after that all I had was problems. Transmission exhaust system and computer board all of this happened one after another total cost over $10,000. Toyota did not want to take responsibility.