P1151 error code after replacing pump from p1121 code?

Hey All -

Been lurking on this sub for years after buying my first Prius (2008, purchased in 2016). Back in March, I had my coolant pump/valve replaced at a local shop (not dealer) after my check engine light appeared and fired a p1121 code. About 2 weeks later, check engine light came back on and it fired code p1151. I took it back to the shop and they said my coolant levels were low. They filled it up and the light went away for a while but comes back intermittently now. The light will come on for a couple days but then go away for a couple weeks. On for a day, off for a month. Always firing p1151. This morning it came back on after being off since June. I've never seen any leaks under the car besides the typical A/C drips.

• Any thoughts on what could keep triggering this code sporadically?
• Are there some things I could troubleshoot or fix on my own (guy who's good at following instructions but not great at knowing car stuff)?

Thanks in advance!

 

Thanks for the reply! I did see that thread when searching for answers, but it seems like that person's Prius had an accident which caused damage to the coolant heat tank, which is different from my situation so I wasn't sure if it applied.

I haven't checked the coolant level myself yet, though I plan to tonight after work (and after letting my car rest a bit it seems).

Would hoses being reversed create an intermittent engine light? That seems like something that wouldn't necessary work itself out?

 

Ah, thanks. The light went off again last night and then I checked the coolant levels in both tanks after the engine cooled down a few hours - both at the full line.

If I need a new CHRS tank, does anyone know what type of issues I'm creating by continuing to drive my car? The first code was thrown around March so I'd guess I've been driving on it since then despite the light only showing for probably 10 days off and on.

 

Ah - good to know! Yes, I meant the overflow tank and the radiator. Both to the full line. No emissions testing in Michigan so I might be OK.

I didn't ask them at the time and it's been about 6 months from the service so they might not remember or have it marked down properly. I'll check with them but I'm guessing I won't get much info out of that. Otherwise, I might just go to the Toyota dealership and pay for a coolant flush and make sure they do it properly and then hope for no more codes.

Thanks again for all the insight and help! It sounds like I'm probably OK driving with an intermittent p1151 code but that I might also be able to fix with a coolant flush. I'll update the thread when I do the coolant flush.