About six months ago, I purchased a “genuine” Toyota coolant control valve (part #16670-21010) from eBay and installed it on my 2009 Prius. At the time, I pinched the hose during the replacement and did not fully bleed the ICE coolant system. Instead, I just topped off the coolant over the following weeks as needed. Recently, I encountered a check engine light. After scanning the codes with my OBDII reader, I received the following: P1121: Coolant Flow Control Valve Position Sensor Stuck P1123: Throttle Position Sensor In Range But Higher Than Expected Unfortunately, this suggests that the replacement valve has already failed. I’ll now be replacing it again, but this time I’ll be purchasing a verified OEM part directly from a local Toyota dealership. While I’m doing that, I’m also considering replacing the inverter pump (part number G9020-47031) as a preventative measure. My concern now is properly bleeding both systems. Since the coolant control valve is part of the ICE loop and the inverter pump is part of the hybrid/inverter loop, and they operate independently, I’m wondering is it okay to pinch the hoses and avoid fully bleeding the systems again? What are the risks of not bleeding the systems correctly?
That code does not mean that; It is also a coolant control valve problem. It actually means the CCV position sensor circuit is high. The code is set when the water valve position sensor voltage remains above 4.8 V for 2 seconds or more. I wouldn't worry about the inverter coolant pump at this time. As you note, it is in a different coolant system loop, so it's not like you will save any labor or coolant by doing it now. If you are reasonably sure the inverter pump is coming up for 100,000 miles, then do it. Pinching the hoses is fine to do if the coolant is a long way off from needing to be changed right now, and shouldn't introduce any significant air into the system. In any case, the inverter loop is pretty easy to bleed. FYI, that "genuine" pump was likely counterfeit or a poorly made aftermarket. There is a Chinese company called Genuine and they market their knock-off products as genuine because that's the name of their company.
Thanks for catching that. The OP didn't seem to be misled by it, but it would be bad to have a thread sitting here that other people might land on from Google and think that's what the code means. P1 codes you have to be extra careful with, because they are manufacturer defined. The wrong (for a Prius) fortune cookie about "throttle position" is probably the totally right fortune cookie for P1123 in some different make/model of car. But a scan tool shouldn't just show you random manufacturer-defined fortune cookies no matter what kind of car it's plugged into. Bad scan tool. No biscuit. If it doesn't contain a database with the right fortune cookies for each type of car, it could at least show you all the known fortune cookies for that code across all cars ... or it could show you just the code, so you would know you'd better look it up in the correct repair manual, which is where you know you'll get the right info.
Sorry, I'm having trouble following along. Does this basically mean that the coolant control valve that I bought is a poorly-made aftermarket product? And does this mean that I don't need to bleed my system when replacing the coolant control valve and the inverter pump?
That is a possibility, probable, even. You will still need to bleed and remove air from both systems, but if you pinch the hoses, it will likely be a lot less effort to bleed them. You would pinch the hoses if the coolant was not due for a change to save on coolant cost.
