My 100 000 km scheduled Maintenance adventure

Hello everyone!

I have to share with you my adventure with the last scheduled maintenance.

First things first: I live in Poland, the dealer knows me since many years already.

My 2010 Prius has now a little over 100 000 km driven, I decided to do a coolant change, even if the dealer says, it is not necessary yet.
My coolant was really stinking...
The car is now 13 years old, the coolant is not younger - decision - change.

After talking to the dealer, we decided to do the normal 100 000 km scheduled checks plus coolant change in the ICE only.

After a few hours the car spent with the mechanics, my car should be ready, but I see them doing something at my car with the diagnostic laptop.
I ask, what is going on, the answer: there is an error, they will delete it, and I can drive home.
OK - done, I get into my car and see the golden engine icon coming on again on my combination meter - nice. I call the mechanics, they want to connect the laptop again: "it can happen, there has to be air trapped in the hoses".

I told them, I can delete the error myself - "Oh! OK, please, do it!".

Scanned OBD2 with my phone, found the error (P0C73 "Motor Electronics Coolant Pump "A" Control Performance", whatever it means), deleted it.

After few meters driven, the error comes on again... OK - that's too much - I'm going to talk to the supervisor. He says, I get another car and can drive home, they will look into the problem - the coolant pump in the electronics cooling system can be bad...

Me - "What? We didn't want to do anything with this cooling system?"

He - "Oh! There was coolant in the bucket left, we decided to change it in the small cooling system too."

Nice! I do not believe, that the pump died accidentally exact at the moment, they changed the fluid...

Me - "OK - look into it, I'm driving home with your car, thank you!"

Short after I got home, I get a call from Toyota: "Your car is fixed!"

Me: "Can I talk to the mechanic, who changed the fluid?"
He: "Nonono, they are all going to go home now... Please come tomorrow morning, the mechanic will be here, ready to talk to you."

OK - next day I visit my Toyota dealer and meet the mechanic.

Mechanic: "It is all your fault!" (little smiling)
Me: "What?? How??"
Mechanic: "I'll show you."

He takes me to my car, pops the engine hood open and points at the hoses going from and to the reservoir of the small cooling system.
"You must have been doing something with the hoses, they were routed falsely."

I had to admit, I didn't do anything to the hoses, but as I bought the car used, I noticed, that one of the hoses was leaning badly on the fuse box, so I decided to protect it a little with a spiral harness protector, but I did not change the hoses position...

So, after short discussion with the mechanic, it was clear, that the previous owner or his mechanics changed the position of the hoses.
The hose going from the container to the pump was _higher_ as the hose going back to the container.
Most probably, this caused problems for the pump, to get all the air out of the system and lastly caused the (a little misleading) error.

I will attach two pictures showing the hoses in the wrong and the right positions.

For me - problem solved, the error is gone.

I know, many things have to come together, to render this situation, but I wanted to describe this for the community.

Thank you for reading such a long post

Mat