2005 Prius P0810 and red triangle 191K miles

I have a Red triangle and code P0810 and P0420. Before I get into this I want you to know that I have always done all the maintenance to this vehicle. Oil synthetic every 5K. .Transmission fluid every 60K. Coolant has been changed one time. Traction battery was new in summer of 2017. I have tools and have lots of experience working on cars. Have any of you had this issue? I need to read with a better computer but the A/C stopped working when this code set. I was driving short distances with the a/c on low and stopping 5 minutes at each stop. Dan anyone help give any insight? Google says clutch sensor but prius is not a manual transmission. I can talk to someone on the phone if you send me a message. Thank you. I do not have a job now and I hope it does not cost much. Please Advise.

 

I have a scangauge II but it is raining out and I have the Enhanced version of Autoengunity so I can read at the sensor level if I need to. I do not have a garage and it is pouring.

 

I have changed the downstream O2 sensor with one I purchased years ago and was in storage for a while. Bosch brand. Coolant was flowing thru the inverter fill cap area so the pump is pumping. It is possible that it is pumping slow but the flow looks like it did in previous flow checks for maintenance checks I performed. I cleared all codes and has been running well for two days now. I will post more if there are other issues. Thank you all for replying and the input. I am very happy to have almost 200K miles. About 8500 to go.