Hey folks, The P1116 and P1121 codes have shown up on my 2009 Gen II Prius about a month ago. The CEL is intermittent - it will disappear on its own within a few drive cycles to a week, only to come back again. I'm not sure what to do next - should I go ahead and replace the three-way coolant valve or water pump or both? Of note I also hear a "push-pull" noise from the engine compartment. Sometimes it persists through an entire drive (my trips are usually short, under 30 minutes) or sometimes it will only happen upon a cold start then stop after a few minutes of driving. Any ideas of what the noise indicates? It sure sounds like some sort of valve or piston opening and closing. It's faint so I've "enhanced" it to make it louder. Apparently I can't upload .wav's here, so I placed it on dropbox. And since I only have one post, I can't directly link to it. So I will post three replies in order to paste in the link. Any ideas? Thanks!
About 60,000. I'm away from her now, up in NY with family. Here's the link to the engine noise that I recorded before I left: Dropbox - Prius Noise - enhanced.wav
3-way coolant control valve might be a root cause of P1116. It could be stuck in the wrong position, causing the DTC P1116 (COOLANT TEMPERATURE SENSOR CIRCUIT STACK FOR COOLANT HEAT STORAGE SYSTEM). As you noticed, the CEL is intermittent b/c the valve is intermittently stuck in the wrong position for any duration of the following: seconds, minutes, hours, days, weeks. Since you live in a cold environment, I would get that valve replaced before winter comes. If the valve is stuck in the wrong position, you could be w/o cabin heat. I listened to the wave sound file. Definitely not the typical sound of a "squeeky" CHRS pump; at least for the ones I have heard.
