Prius Hybrid System Issue engine runs fine

Hello we have a High Milage (610,000 KM) Prius with a "Check Hybrid System" Error on the dashboard. I would appreciate peoples input on repairing the root cause of the issue please

History of Hybrid System Errors
A few Thousand miles ago i replaced the the DC/DC inverter on the vehicle following the car Breaking down .in that instance the vehicle cut out under hard acceleration and then the car would only drive on electric power at 30 MPH max ,but if I did a full reset and removed the fuse for the hybrid system and the starer battery ,the petrol engine would switch on for around 30 seconds and I could drive the vehicle on petrol power until the car went into limp mode again a few seconds later.

i used Delphi Scan software to determine the fault and the error came up as
P0A94 DC/DC Converter
I then fitted New Inverter (but not a new inverter Pump) and the car drove perfect until today

Today the following happend
The car all of a sudden gave the same error on the dashboard
"Check Hybrid System" but this time the symptoms were different in the sense that
1. The Petrol engine would remain on and I could drive normally .
2. the electric hybrid system does not seem to be adding drive or power to the drive train only recovering energy .

Symptoms leading upto todays Error Message
When driving it earlier in the day the car was also doing some strange things like

1.the car seemed like it was constantley in Gearbox B mode as going downhill in Gearbox Drive mode the car was making that loud regeneration engine braking noise it makes when as if it was in B mode.

2. when I was stationary the petrol motor would continue to run at high rpm as if I was trying to recharge the battery and the only way I stopped this was by turning the car off by pressing the power button

3.looking at the hybrid system annotations on the dash board while accelerating on petrol power at 50 MPH the indicator showed the petrol engine to be off and the car to be recovering energy only as if I was coasting to a stop !

4.after using the Delphi scan tool no error is showing at all !?

My questions

1.is it possible that the MG2 is staying engaged all the time ,as there is a faulty switch or solenoid ?
2.has anyone used an engine flush to good effect with the same symptoms and did it resolve the issue?
3.is it possible I bent the input shaft as I left foot brake and sometimes I have the break and accelerator on at the same time for a brief overlapping period .or while doing hard acceleration from a standstill I may leave the break pedal slightly down as I apply full acceleration ?
4. has anyone had the same issues ?
5.are there any common issues with the gearbox as a whole ? and what goes wrong internally on the gearbox ?
6.do the bearings wear or planetary gears has anyone replaced these ?

 

quick update I disconnected the battery and the main hybrid battery fuse to try and clear the check engine lights ands it did not work so I tried doing a hard launch in reverse twice to determine if anything was making a noise in reverse and then rebooted the car and the error are gone and after a brutal driver to invoke the error again I can say the car drives fine.

what are the symptoms for a faulty inverter water pump?
will a faulty inverter water pump show up on techstream ?
are there any other relays ,solenoids ,connections or circuits that could be causing these issues ?

 

I turned the car on and there is no movement in the Coolant reservoir tank for the inverter is it meant to run constantly even when the car has just started

I also got the codes

U0293 Lost Communication With Hybrid Powertrain Control Module
POA0D-high voltage system interlock circuit high- which is the hybrid battery fuse /isolater

 

Thank you all for you're replys
I recently fitted a new DC/DC inverter less than 10,000 miles ago
we used the Delph software with the OBD connector and it gave the codes I mentioned above

on a side note Delphi software and hardware does work with the Prius Gen 3 .
it has a data set called Multifunction and then you go to hybrid system and it can check the hybrid system (to a limited extent )
also has a flight mode so you can test certain data while driving in realtime
and also has the ability to alter some settings ie bleed the brakes,test solenoids etc.

I cleared the codes on the car and it is now
1.driving as per normal
2.with no warning lights
3. and no limp mode or Check Hybrid System Warning.

but it was a mistake on my part to get the Error codes cleared as I later went to get the car properly scanned using a Snap On Modus Ultra and NO codes would appear(even after the long drive)
This Snapon machine would have pinpointed the issue so big mistake to clear the codes and now the car will not reproduce the same symptoms and won't display any errors and is driving as normal .

I was thinking the same thing as jerry
That I need to make the car get hot to invoke the error in the hybrid system by putting it under load.
so I drove it in a manner to stress the hybrid system as much as possible but to no Avail ,the car will not reproduce the same error .

I feel it may be the Inverter water Pump as it makes sense as it intermittently failing may have caused my previous inverter to overhead and fail before I replaced it and could be once again causing the DC/DC inverter to act strangely .

I will try and make the car produce the same errors then get it scanned on a Snap On Modus Ultra