Coolant Control Valve Leak w/P0117 code?

Short description: Got a p0117 engine code and engine started overheating on my 2006 Prius. Drove it home and noticed a lot of coolant pooled on top of the lower engine splash shield. Followed the evidence and it seems to be coming from the coolant control valve (see photos). The weird thing is, I'm not getting any other codes that seem to usually be associated with a malfunction in this component. I just wanted to confirm there cannot be any other source for this leak before I replace this component.

Slightly longer description: About 2 weeks ago, I started randomly getting red triangle warnings while I was driving that would pop up for a few seconds, then go away. At first it only happened once every few drives, then I took it on one ~45 min highway trip and the warnings kept popping up and disappearing constantly the entire drive. I plugged in my ODBII scanner and searched for codes while the triangle was still active and no codes were found. All fluids SEEMED normal and I didn't see any evidence of leaking anywhere after this drive. Finally, about a week later, I got a red triangle AND an overheating warning followed by a check engine light. Finally, I got two p0117 codes.

Got under the vehicle and saw a lot of coolant pooled on top of the lower splash shields, but it was dark, so I could not determine the exact source at this time. I check later the next day and the coolant all seemed to be coming from the driver side of the engine bay between the inverter and driver side wheel. Most of the liquid was gone at this point, but the hose leading down from the coolant control valve had a lot of whitish streaks leading to more streaks and a few wet spots on hoses/wire/components below the control valve. From above, I saw coolant pooled on top of the control and no evidence of leaking anywhere above or adjacent to this. See photos from both above and below.

I'm happy to order and replace this component, but as I look into this problem online, I haven't found any source where a solitary p0117 code was associated with a leaking/faulty coolant control valve. Are there any other possible explanations here? Let me know if I can provide more details.

Thanks!

 

I definitely agree, but just to be clear: the P0117 didn’t trigger until the engine overheated. Could the code have resulted from the overheating which was itself caused by the leak? Or could the code be pointing to another initial failure (e.g. water pump) that led to overheating which put pressure on the system and led to the leak? Or do you think the leak and the sensor issue are separate?

Sorry if this is getting convoluted. I’m going to add some more coolant to the system and try and locate the leak following your suggestion. The two components I’m targeting right now are the water pump and the coolant control valve. I don’t think the wiring or sensor itself is malfunctioning since the P0117 code was only triggered once the engine was, in fact, overheating, but do tell me if that assumption is incorrect.

If you have any other suggestions, please let me know!

Thanks so much!

 

Alright. I put some more coolant into the system just to see where the leak was. Definitely seems to be coming from the control valve, possible the point at which the bottom hose (to the heat storage tank) connects to the valve. I drained the system and pulled off the valve and that lower hose along with it. I can’t see anything with either the valve or the hose that would cause a leak but I’m going to get a replacement tomorrow and see if that fixes the problem.

 

Well, I just don’t know what’s going on here. I replaced the 3-way control valve and refilled the system with coolant. No leaks this time and no codes were popping up, so I was feeling real good about myself. Decided to take it for a quick test drive and I noticed it getting on the hotter end of acceptable operating temps (200-210 F) pretty quickly while driving down my road at around 40-45 mph. I then got on a rural highway and took it up to 60 mph for a bit and the temp shot up to 230 pretty quick and then slowly crept up to 250 even when I had brought the speed down. At this point it threw a p1121 code which I believe suggests something wrong with the part I JUST changed. I got it home right away but at this point it had started pouring down rain and I’ve got no covered area to park my car, so I have not been able to properly inspect the engine again but a brief peek inside did suggest the possibility of a separate leak or overflowing coolant somewhere but it also could just be water from the heavy rain pooling in my lower engine covers.

Obviously, I need more information, but I’m trying to plan for next steps and I’m at a loss. Could it be an electronic issue (hinted at with the previous p0117 code that is no longer popping up) suggestion perhaps the 3 way valve or some other component isn’t being powered properly and so coolant isn’t moving through the system as it should? What else should I be testing?

One other hint, and possibly a very stupid thing I did: when I got in the car to do the test drive there was no check engine light on but I ran a check and it came up with six codes that I recall being 2 each of the following: p0117, p0118, and p1121. I chalked these up to having been thrown while I was replacing the valve and filling and burping the coolant system so I cleared them and figured they would come back again if there actually was a problem, but maybe that’s not the case and I just ignored the evidence of the current problem.

Again, any guidance here would be very much appreciated!

 

It doesn’t seem like I can delete my last posts while it’s still pending review, but PLEASE IGNORE IT! The problem is resolved. I’m just a newbie at this and hadn’t fully gotten the air out of the system. Needed another liter or so of coolant and 30 more minutes of cycling the engine to fully finish the job.

If anything goes wrong in the next few days, I will follow up but otherwise consider this problem resolved.