p0031 and p1150 - Bank 2 Sensor 1? Or Coolant Clog?

Hi everyone! Hope ya'll can help me get to the bottom of this before I go crazy, I THINK I'm on the right track.

I'm unsure if I have two separate issues going on that just happened together, or compounded each other.

First, I replaced the ICE with a junkyard one after getting really bad knocking. Original had 230k miles, replacement ~180k. Seemed all good for a week or two.

Only error I'd get was the red triangle with "coolant temp" logo , occasionally, and it went away and drove fine. My buddy said "maybe still some air bubbles in the coolant" - we tried to run it with the cap off for a while, didn't seem to help. I see now recommendations to run the pump only using a multimeter on the , and fill it from the cap while doing so. This video is what I planned to do next:

However, I suddenly started getting bad bad shaking and misfiring, and pulled error codes for all the spark plugs, p0031 and p1150 - idles VERY rough, and changes dramatically when I shift between Drive, Park, Reverse, and Neutral, getting better and worse in different gears. (So i'm thinking sensors and wiring etc)

I replaced all the spark plugs and the O2 sensor on the catalytic converter. (Bank 1 sensor 1) (p0031)

This didn't seem to help at all. (though I'm sure they all needed a replacing anyway)

However, I'm seeing two different explanations for p1150:

"Bank 2 Sensor 1" - and COOLANT PATH CLOG UP FOR COOLANT HEAT STORAGE SYSTEM

Could the air bubbles be causing such bad misfiring after all?

I've seen people suggest to fill the coolant in the reservoir up front, but others say ONLY under the pressure cap?

And I was under the impression that the prius gen 2 only has a Bank 1 Sensor 1 (downstream on the side of catalytic converter) and Bank 1 Sensor 2 (upstream on the right side of engine)

Could code p1150 be referring to the upstream sensor, on the side of the engine? I replaced one, might as well the other? (it's just a bit more annoying to get to it looks like)

My next plan was to :

-Check the catalytic converter system again for cracks and holes (i'll feel silly if there's just a big hole I'm missing that is causing this

-Run the pump to try to clear air bubbles

-replace upstream sensor if those don't work?
found this video on it:

basically have to remove a few things around the engine and go in beside it, not the worst....
this was my downstream sensor next to the catalytic converter:
https://www.napaonline.com/en/p/DEN2344623?impressionRank=2
is this the correct upstream one? why so much more expensive?
https://www.napaonline.com/en/p/DEN2349056?impressionRank=3

Any other obvious things I'm missing?

 

Ok, so according to this doc about the p1150 codes on the prius gen 2 :
https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/2054m/cip1150a.pdf

CHS tank outlet temperature sensor
Water valve (Coolant flow control valve)
Cooling system (clogging)
ECM

Coolant path clog / air bubbles is most likely cause? I'll try to check the sensors too... that would explain it happenin suddenly?

The CHS tank is the thermos that holds hot coolant, is there an easy way to test the sensor?

The valve I assume is fine...

And the ECM is like the computer module? Bad news I assume if that's it? Any easy way to test?


P0136 is the code for the upstream sensor correct? I should be safe not changing it?

I don't know what this means.

 

Shoot so even without the p0136 code it could be the upstream sensor? Was hoping to not change that one too, but I'm running out of options, and didn't want to take it to the Toyota dealership...

How do you check the head gasket?

 

Thanks ok I'll take a look at that...

I think I've isolated it (finally) though:

I tried to jump the water pump using a multimeter like shown here:

However, I'm not getting anything from the pump, while confirming it's "connected" by hearing the beep on my multimeter... Unless I'm doing something wrong, I've got a broken water pump. I tried it with the car off and with the car "almost on" (two button presses with no brake pedal) and can't get it to go.

Double checking my multimeter settings, but if it's connected (and I hear the beep) then it should be going, correct?

 

Hmmm ok I was wrong after all and have the water pump running now... it's sucking A LOT of coolant in, and I know I'm supposed to bleed it after too.... Crossing my fingers either this or another inspection of the exhaust system for holes will fix it...

Bad bad misfires and shaking, but since it's always changing sounds between Neutral, Park, Reverse, etc, it's GOT to be a fuel/air mixture somewhere, right? I was thinking for some reason the coolant could be involved? (not getting the right reading from the sensors because of it?)

 

Yeah so damn, I keep putting it in and it keeps sucking it somewhere... Maybe I just need even more coolant.

Question however: While I'm jumping the electric pump, I DO NOT see the coolant in the Inverter Coolant System Resevoir moving or bubbling at all (the one next to the electric motor). Is that ok? Does this electric pump only do the other system?

Is there a way to jump THAT system? Because when I get the car started, I can't tell if that's working (i'm getting such shaking from the bad air/gas mixture, but I don't think it's 'bubbling' in there like it should) Is that a different pump, and could that be leading to my air/gas mixture being off so bad?

I was getting the p0031 code, which is the downstream (next to the catalytic converter)? I changed that, but maybe there's a way to check if it's getting the right power? Checked fuses and such, and see this listed on that doc:

Open or short in heater circuit of A/F sensor A/F sensor heater EFI M relay (integration relay) ECM

I see directions to check the voltage of the sensor while the car is on, but I'm running so rough and blowing such exhaust, I don't want to do that. The ECM module I hope is not the problem, but don't know how to check it. The A/F sensor heater is built into the sensor, yes? So I changed the sensor entirely, should be fine.

>>>
Here is the workup for DTC P0136, P0137, P0138 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8CPDF%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0136.pdf

I used the code reader at autozone, but now I'm back home it's running even worse, don't want to risk going out there. Had a cheap bluetooth one, can't find it!

>>
Regarding the water valve, it is possibly to switch the hoses around, and has happened before.

Now that's interesting, meaning when I put the engine back in, i could've hooked a hose up wrong? Could you explain what you mean?

 

Also the other code was p1150, which shows this: https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/2054m/cip1150a.pdf

CHS tank outlet temperature sensor
Water valve (Coolant flow control valve)
Cooling system (clogging)
ECM

so unfortunately also the ECM is listed there, hope that's not the problem.... not sure how to check the CHS tank sensor? And the water valve would be a literal clog? Got just a few more things to try before finally admitting defeat and going to Toyota..... It's an old one though, so not sure what they'll say.

 

Ok I really hope I didn't **** something up here, but I think I put the wrong coolant in?

When I changed the engine, I think we left the original inverter coolant alone, and I don't think it's had to be filled at all (though I assume we'd lose some from the radiator? But maybe we had it plugged well enough when we put it back on, and the inverter coolant system stays internal, so it's good)

HOWEVER, when I refilled the other side (which just seems to keep sucking coolant in!) I used orange "havoline extended life dex cool" - like this https://www.santmyer.com/wp-content/uploads/2021/03/Havoline-Xtended-Life-Dex-Cool-Antifreeze-Coolant-Concentrate_1-Gal.png

and now doing some searches about it is getting me scared. I was driving a few weeks before the bad misfires, and I think it was also low because I didn't realize how much it sucked in. Could the coolant be the culprit? Worth draining and getting the right stuff? Or should I keep filling it until it can't take more?

 

Yeah I changed the spark plugs when I got the misfires, then the downstream sensor. Or do you mean the cap on top of the spark plugs, those big gray tubes with the electrics (whatever those are called)? I'll check for coolant smell, essentially the head gasket leaks and lets coolant in, it burns rough and misfires?