Hello, I have a Gen 2 with ~180k miles that was throwing the P1121 & P1116. I replaced the 3-way coolant control valve with a used OEM part and I followed this video: I was able to get the part in without much loss of coolant. I reset the codes, refilled the coolant and took the car for a drive. A couple minutes later I got just got the single P1121 code. Referencing a document I found, I get this: " If DTC P1121 is detected, coolant passages may be clogged." The same DTC document for the P1116 code said to check for clogging in the coolant system. My question is how do you check for coolant system clogs? On an unrelated note, does anyone know where I can find a full book of these DTC documents? I find them very helpful.
I do not "check for system clogs". Instead, I see what the system does. Turn the heater off when I park for the night. Next morning, I turn the car "ignition on" (power button x2 - foot NOT on the brake). Hook up my scantool (one that has enhanced Prius specific ECM data). I look at ECT (engine coolant) and CHS (coolant heat storage) temperature sensors. Both should be near ambient. Now power on to "ready". The CHS pump should run for around 5 seconds. CHS (aka water outlet) and ECT (aka coolant) should both go up around 100°F then drop some. After that then the engine starts up. Here's a graph of my 2006 on a cold morning. (It goes from left to right) All that said, I have yet to see P1121 that wasn't a glitch with the position sensor in the 3-way water valve (but it is possible). The only way I could "see" the glitch is to use an oscilloscope. I have also seen problems where the hoses to the valve were swapped around. Posted via the PriusChat mobile app.
There are several error codes for the coolant storage thermos system. The most common problems are a faulty three-way valve, transfer pump, temperature sensors, and clogged system. https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/2054m/cip1115.pdf https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/2054m/cip1116.pdf https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/2054m/cip1120a.pdf
