I noticed a puddle of coolant in my driveway every time I drive my Prius. Upon closer inspection, the heater valve is leaking. Removal is a little bit of a struggle since the space is tight to remove the hoses. I access the lower hose down under from the CHS tank. Never buy a Dorman heater valve (or the chinesium junk in Amazon) OEM only cost $113 online with shipping included and it will be worry free that it will last for a long time.
I had to replace mine last year and the aftermarket ones were only about $10-$15 cheaper than OEM. Totally not worth the risk considering all of the reports of aftermarket only lasting a couple of years, whereas OEM is 10+. The one gripe I had was that my local parts department couldn't find the right part when I went in. I ended up ordering mine from a dealer with an online parts store.
