Hi Everyone, So I just picked up my 2009 Prius from having its 100K service today and as I'm driving home the Check Engine light came on. I turned back around the guys at the auto shop read the codes and it was P1116 and P1150. I think I had the P1116 code before. (According to my service records, in March 2018 I replaced the Auxiliary Water Pump -- not sure if that would be for that code?) Anyway, since the issue is back and now there are two codes I wanted to see if anyone on here had any ideas. The guys at the shop said it might be "electrical" and asked me to drop it off for a few days so they could dig into it a little more. I'd love to hear if anyone here had any ideas first. Thanks! John
Both of those codes are for the coolant heat storage tank/system and flow control valve.. The thermos hiding behind the driver headlight. P1116: Coolant temperature sensor circuit stuck for coolant heat storage system could be: chst outlet temperature sensor, cooling system clogging P1150: Coolant Path Clog Up for CHST could be: outlet temperature sensor, coolant flow control valve, cooling system clogging, heat storage tank, ECM
Thanks. So it sounds like it's not the water pump (which would've been covered under their warranty). I'll drop it off on Saturday and give them a week with it. Hope it's not too expensive to fix, whatever it is!
Was the engine coolant replaced as part of that 100K mile service? If yes, the most likely cause of the check engine light and the two logged DTC is that air remains in the engine coolant loop. Does the cabin heater work? Do you hear air gurgling in the cabin heater core? Check the fluid level both in the coolant reservoir behind the radiator and in the radiator itself.
Actually it wasn’t part of the service. I had asked about replacing the coolant but he reminded me that they replaced it when they did an earlier service (the last time this code came up!) When they replaced the coolant that time, I did get the check engine light and they bled air from the system again. But that was a while ago now. (I also did have an issue with a sloshing liquid sound when I started the car - but I solved that with a little extra coolant and one of your earlier posts!) Again, both of those issues are at least a year ago now so I’m kind of at a loss. I guess it wouldn’t hurt to check the coolant level in those two spots anyway and go from there?
Yes, pls check the coolant level. If it is low, look at the engine coolant pump for whitish or pinkish stains on the interior of the pump pulley, and deposited on the air conditioner compressor below the coolant pump. If you see that, this is evidence that coolant is leaking from the pump bearing and the pump will need to be replaced.
