3rd gen Prius where is upper radiator hose???

At the risk of repetition, what P261B means is that the ECM thinks the WP rpm is less than 900. Whether the ECM is right about that is one of the things the human needs to find out.

 

I know it's been loong... but were you able to figure out the problem?

 

Hey @ChapmanF

I've a Gen3 R&D car I'm making plans for regarding how cool I can keep the enginge running and I'm going to add an additional water temp gauge in the dash that's hardwired to a sensor that screws into a coupling and I'm thinking the best place to put that additional sensor is in the pipe that you highlighted in red? Would that be a location that other sensors don't cover?

Basically trying to figure out where all the temp sensors are and where there's gaps in the data... What would you suggest? Someone told me monitoring water pump temperature might be useful...

 

Just two temperature sensors. One on the cylinder head near the water outlet, and one at the top of the hose coming back up from the EHRS exchanger.