Hey guys so my girlfriends prius got the p1121 code, so I ordered the part with coolant and started the process and thought I finishes, it was kinda hard finding support for this car online, and even with so many different ways of how people did things I couldn't find a true answer anyways. I started by draining coolant from the yellow petcock under the heat storage tank, it drained for about 15 minutes. Once that was done I went to the coolant control valve, first unplugging and the starting top to bottom on the three hoses, and then the two mounting bolts, swapped the part connected everything back up and then it came to refilling the coolant, this is where I couldn't find anything for sure. I noticed that the overflow tank didn't empty, but I'm sure that runs on vacuum, but I tried first to put the car in inspection mode to leave the engine running, and the fill a little at a time through the radiator, finally it looked like it was filled, driving home, a warning popped up saying coolant. Can't find anything leaks and it won't take more coolant, so I'm wondering if there is a better way to bleed the system? Also that night driving home heater worked just as normal, but now won't blow and warmth at all, what could be to cause of this, while dealing with the p1121 code? Thanks
Although it probably is too late for you now, my advice is that you need to keep track of how much engine coolant you drained out so that you will know how much new coolant you must add before you declare victory over this project. Your engine coolant loop definitely has air trapped within. See my posts #22 and #42 from the following string and follow my discussion about how to purge air out. Changing engine coolant | Page 2 | PriusChat If you are looking for a "true" answer, subscribe to techinfo.toyota.com to access factory repair manual info.
Everything Mr Wong said. And my Bentley manual, often useless, gives good information on how to bleed both coolant loops. I did this job a few weeks ago and it went very well thanks to information in the book and on this site. Running the coolant pump manually and using the radiator bleeder valve were critical parts of the process.
