Hey priuschat , I have Prius with 250k miles.Yesterday I replaced the inverter coolant pump, changed the coolant and did a bleed. I’m getting a p1121 and p0420 code. What steps should I follow to fix this issue. Should I directly replace the coolant control valve? Couple months ago the red triangle light would come on together with the engine light and would disappear after filling the radiator cap and the tank next to it with water. Thats what my girlfriend was told by the dealer she got the car from. It seemed okay back then but now it looks like a dumb idea, could this be related to the issue with p1121? Also, my car gets around 35-40mpg and AC works fine when turning to max heat. The radiatior cap is not hot, not sure if it has to be but thats what I remember reading it somewhere. I also checked the hose that go to the coolant control valve, all 3 hose are extremely hot. Also, there is another big hose above the coolant control valve which is extremely hot as well. I have attached a picture. When I do the vehicle signal check mode on the screen, The battery voltage shows as 13.1V when driving. Thats all the info that I have for now. How should I troubleshoot, any ideas? and thanks in advance!
Keep following all the information on here about getting air out of the cooling system.... Then if that doesn't settle the code down you'll have to replace the valve... Once that's sorted out you can try to get rid of P0420 with new plugs and cleaning of intake manifold, MAFsensor, etc. Then if that doesn't work the good news is you can install an aftermarket Cat for $200 and precious metal harvesters will pay you $1500 for your original cat, which will cover you repair costs for everything.
Thank you! I will try to get the air out. Since we filled the radiator with water should I change the coolant-water mixture by draining it? Also, I forgot to mention, the catalytic converter was stolen and we replaced it with an aftermarket part together with the O2 downstream sensor. Not sure if we forgot to replace anything else.
