Coolant disappearing and can't find where

Move cylinder 1 spark plug to #4 and #1 ignition coil to #3. Clear your codes and see if the problem moves. By doing this, your isolating ignition system fault. If you throw another P0301, you know that the issue is isolated to cylinder #1. That means you have either a mechanical and/or injector failure in #1.
If the problem moves, then it's whatever part you moved to either #3 or #4 is defective.

If coolant isn't hitting the ground or leaking onto your front floor mats, see #12 of this thread - those are the only other places they can go. That white smoke out the tailpipe doesn't apply to these new modern engines - they run too lean. You'll see white smoke out of your tailpipe on cold damp mornings, until the condensation burns out of it.

Hope this helps....

 

So did you have coolant loss through the exhaust heat exchanger, and/or was there a diagnostic done, say by dealership? If so, how long was it going on before you did the bypass? Did you try to get the exhaust heat recovery replaced under warranty, but were denied? Or dealership is waiting on "back ordered parts"?

Trying to fill in the history.

 

Everything is sad. A piston cleaned of carbon deposits with a coolant leak is a clear indicator of an engine overhaul with a gasket replacement.

 

If doing boroscope inspection, you can exacerbate coolant leakage past the head gasket, by removing the engine coolant reservoir cap, pushing on a stopper with a through-tube and applying air pressure.

In the attached pic, I used a T-connection as the "through tube", since that's what I had. The side channel is sealed with 2-part epoxy. The pressure/vacuum valve hose kept kicking the hose off, so I added a bit of bent steel wire to lock it.

I might try this sometime, with a simple fluid transfer syringe, with a couple of check valves, arranged so it'll hold pressure.

 

You need a good dual view borescope to actually see the pistons and sometimes the coolant leaking in under prescribed conditions.

White smoke from a hg leak can be seen at the exhaust when the problem is advanced. Yours could easily be advanced. Requires rev'ing the engine and an observer.

 

This bodes good for the head gasket.

What's the miles on it, now, and/or when you got it? It might have been eligible for the exhaust heat recovery component (and catalytic converter, it's all on piece). It may still be. Maybe last owner was stonewalled by dealership when in fact Toyota would have covered it. Or the part was endlessly back-ordered.

 

Just replace the engine and be done with it. the rest is a pretty good car

 

Well; it seems you also have an ignition issue too. I'd nail down the ignition issue now - so your not dealing with multiple problems when you do the head gasket. Otherwise, you won't know if you messed up the head gasket repair and/or introduced another issue.
There's no telling how long the previous owner drove that car with the leaking EGHE (exhaust gas heat exchanger) and how many times he/she overheated it and how badly. You won't find anything on carfax, because the shop that did the work would be admitting to defeating a smog device. Depending on their jurisdiction, they could lose their license. The head and/or engine could be warped and a new head gasket repair isn't going to last very long. That's probably why the previous owner decided to sell the car, while it was 'running' decently. Get rid of the car before it starts costing them major dollars for repairs. The mechanic that did the bypass probably told them there was potential damage to the engine with the overheating. Sorry
A good used engine may be a safer path forward.

Good Luck

 

Possibly; If you've got the time and don't mind doing the work - go for the head gasket repair. If that only last another 10K-20K miles; you'll know you need another engine. It's slightly warped.

Good Luck....

 

It’s checking for exhaust on coolant.

 

Might be why the cars leaking coolant. I doubt I'll be able to guess, for at least a year, maybe longer.

Which bypass did you do? engine bay our U tube at heat exchanger?