"Replace engine / inverter coolant" easy or hard?

For the second gen Prius' there was a recall effort to replace the inverter coolant PUMP because of premature failure. Is this the item you are referring too? The coolant for the inverter/engine is different from that item and are themselves in different reservoirs and must be serviced individually.

If you do the research, you will find that drain and refill of both coolants (they use the same Toyota Red, just different reservoirs) is quite simple.

The inverter pump itself is a bit more involved, but there are videos on YouTube showing how it can be done.

 

Dealerships will give you a price, try them first?

I've changed coolant on various Hondas over the decades, never any issues. But the Prius makes me nervous, not sure if I'd take it on. Apparently very fussy.

 

My posts 22 and 42 in the following string explain how to replace the engine coolant. For North American 2G Prius, this is not quite as easy as some may think due to the presence of the coolant heat recovery system, and a few PC members have posted that their local Toyota dealer service dept failed to do the job correctly, mostly due to not getting air out of the system.
Changing engine coolant | Page 2 | PriusChat

The yellow Lisle funnel is really helpful to make this job easier than it otherwise might be, and I highly recommend it.

Some owners resort to performing a partial drain, just at the radiator, without draining the CHRS canister. However this is inadequate as only ~1/3 of the coolant will be replaced. Even if all three drain cocks are opened, only ~2/3 of the coolant will be drained as the remainder is trapped in the cabin heater core due to the presence of the engine coolant valve, the pump that moves coolant through the heater core when the engine is off, etc.

The 2G inverter coolant drain and replace is not particularly difficult assuming you have a 24 mm socket and can find the correct drain plug on the transaxle case. You don't want to drain the transaxle ATF accidentally. The bleed valve for that system is hiding under the large black plastic panel that covers the radiator.

As an engineer, you would benefit from access to the factory repair manual information, which you can access at techinfo.toyota.com

My guess is that you would pay ~$200 for the dealer to drain and replace both coolants. You need three gallons of Toyota Super Long Life Coolant, which will cost ~$65 or $70.