We have a 2001 Prius, bought used last year for our daughter. It has a little over 100,000 miles. Fairly new battery for the electric part. In the fall it stalled, dealer said need to replace the inverter converter for $4000. Car is only worth about $4000 and we had just paid $4000 for it. We continued to drive with no more problems. Took it in to a dealer for service a few weeks ago, serviced, no problems noted. Last week our daughter was driving to Florida and it stalled on the interstate. Another dealer said same thing, inverter converter for $4000. He said she could continue to drive it, but it would stall sometimes and she’d have to stop for 1 - 2 hours and then it would restart. We sent her on her way, she broke down 4 more times before her destination. Now it won’t start at all. Any suggestions? I read on the internet that sometimes when that code is thrown it is really just the inverter water pump which is only about $300 to fix. She is in Florida until late July, it appears we’ll have to go get her. We are thinking of trying to fix the inverter water pump and see if it works. Otherwise, we’ll probably junk the car. We are not mechanics, any thoughts or suggestions would be appreciated.
You’ll do better on priuschat.org, you’re asking some very detailed problems about the first gen Prius. Probably best to see if somebody can recommend a decent mechanic in her area.
Have you ever replaced the water pump for the inverter? This is a common problem and they fail regularly after 60 to 70K miles. Should cost $140 for the pump plus labor to install. If your car failing intermittently because of inverter, this is the main culprit.
I assume the car works normally after it sits for a couple days after the car stops due to inverter problem(Big red triangle appears on dashboard). Some other symptoms include AC not working just before the car stops. This sometimes kills inverter. taking care of it as maintenance item will prevent killing of the inverter. I would be wary of the dealer that quoted the $4000. Make sure the person servicing it knows that this car has 2 cooling systems(even dealers screw this one up). If they dont know, I would not let them touch the car.
almostrice, thank you for your response. We haven’t replaced the pump, I don’t think anyone else has either. That is what I was thinking we should try also.
Sorry just noticed the 2001. I am unsure of the 1st gen Prius. The 2004-2009 models have this problem.
check this link out. seems like 1st gens also have problems
Yes, it appears it is fairly common with 1st generation. They recalled the 2004-2009, but not the first generation. 
Replacing expensive parts based on guesswork seldom works out…There ARE wrecked or otherwise scrapped Prius’s available to pick parts from, but which parts? You KNOW the answer from dealership mechanics—$4000. Finding an independent mechanic who is familiar enough with the Prius to successfully repair it using used parts may be easier said than done…
People who wish to buy high-mileage high-tech cars need to educate themselves as to how to maintain and repair them. I suspect the diagnostic equipment needed to diagnose these cars is proprietary to Toyota Dealerships. So now we are back to guess-work…I would just add the four grand to the tuition bill, write it off as an educational expense…