Re: 2001 Prius Major Breakdown.
3. The ICE not starting could also be caused by soot in the intake manifold. I recall there being reports of soot build-up on the butterfly valve or some part or sensor in the intake manifold that causes the engine not to start immediately. Search elsewhere on this site for this problem and repair instructions.
4. If the ICE starts, but the electric motor doesn’t run when the ICE is hot, it may be caused by the hybrid system coolant pump. There are two coolant systems in the Prius; one for the ICE and another for the hybrid system electronics. If this hybrid system electric pump fails, the hybrid module overheats and shuts down. However, you would probably see other codes, in addition to the ones you report.
I would be really hesitant to replace the traction battery without more troubleshooting, as there have been very few failures reported, except when associated with collision damage. Also, the repairs associated with the traction battery and hybrid module are usually replacement of the entire assembly, which is costly.
I would get a second opinion from another Toyota dealer before proceeding further. Or, at least have the dealer call in the factory people to troubleshoot it more thoroughly. Unfortunately, some dealers have much more experience working on hybrid vehicles than others.
If the traction battery or hybrid module must be replaced, check with the dealer and Toyota Zone Manager to see if they will provide free or discounted parts and/or labor as an act of good faith. This is more effective if you have had your vehicle serviced regularly at the dealer. They have helped early Prius owners in many cases to reward the early adopters.
As a last resort, you may be able to get replacement parts from a junk yard or used parts supplier. Although, if the cost is too high, you may wish to trade up to a newer model. The dealer may give a generous allowance on the new vehicle, because of the current market; and it doesn’t cost them much to do the repairs themselves. It’s only costly for us…