blown head gasket P0301 P0302 P0300 ?

Background:
* 2014 Prius with 205k
* bought the car at 150k (was uber) and did right away the EGR cooler (quite clogged)/pipe/valve, new PCV valve and added an Oil Catch Can to prevent future cleanups, cleaned intake manifold (had pool of oil) 4 small holes (also clogged) using @NutzAboutBolts videos
* spark plugs were changed at ~140k (iridium bosh) by prev owner
* car never burns any oil (I believe 2014 has fixed ring redesign), changed every 5-6k, and I get maybe half a finger worth in the OCC (milky smell like gas+oil)

What happened
* got engine light check for P0301 cylinder 1. cleared it and came back but didn't feel misfire
* one morning started the car and bad shaking for 15+ sec, strong smell of gas in the exaust

since EGR should still be clean and newer spark plugs (and unlikely coil going bad especially now that it's 2 cylinder) I thought maybe fuel injector are dirty (gas smell above) so I poured a bottle of Techron Fuel cleaner into my 7gallon filled tank (didn't have luxury of mostly empty tank unlike directions, and syphoning gas didn't work). Decided to drive it one more day about 70 miles.

* mostly cylinder 1 (oh oh) but also occasionally getting cylinder 2, and even a P0300 (multiple misfire)
* notice the coolant appear 2" low (keeping an eye now) but not driving the car anymore since it might be a HG instead of dirty injectors ?
* the few times I noticed shaking was at low rpm or startup

Read here combustion leak detector (blue -> yellow) might not work on prius so didn't order one. have not checked pressure in coolant tank yet. Thinking of using a boriscope to see inside cylinder 1 and see if I see any coolant but wondering if there something easier I should try first.

I did a big preventive maintenance with the EGR to prevent this from happening 50k ago and here am I now. I drive an EV now so this is my daughters car, but I don't know I'll ever buy gas car again...

 

I didn't think about that... but 55k later seems like a long time for that to old up. 150k/10y is when CA hybrid battery warranties expires (I did throuhgly tested the battery with Dr prius app and rejected other cars) so figure that was why, and price reflected that. I assume the only way to know will be to examine the HG if/when I replace it...

Don't have sideway boroscope, only down so will have to wait to drip down

Didn't know about brake booster issues... will have to research that before spending time or $$ replacing HG. She loves her prius (I drove it tons before getting an EV when she was in College/abroad) and the gas mileage (~44mpg) is prety close to my Tesla (electricity is very expensive in Cali).

 

Finally got to try boroscope I bought years ago (for this exact issue I was worry about).

#1 (misfire) looks very wet (car sat for 4 days) - doesn't smell like gas, and if it was oil I woudl expect to be dirtier ? so maybe coolant... Agrrr.
#4 (no code) looks rather clean by comparaison though. tiny bit wet looking spot too ???
#2 (error once) and #3 look totally dry but I realize piston were up so not entire picture and I can't rotate the engine until tomorrow to see...

spark plugs look indentical (will post pic) other than maybe #1 having a bit cleaner (steam clean) edges... all 4 are very sticky (rust color) on the thread. wonder if he put some anti seize or something.

Also wondering about the marking H2 B on cylinder head, and if I have the redesigned late 2014 ones and/or fixes ring or if oil consumption going to be the next issue (none so far, 205k).

 

yeah 4 looks rather clean to me as well yet no error code (just #1 and once #2).

Doubt I will put an engine in given I've paid $6k for it 5 years ago so it has served me well, but then again kkb private party list it for about the same price still which is insane... doesn't make sense to put $3k+ into it now. either I do the hg myself or find a shop that can do it for around $1k... time to call around.

man, so much for Toyota reliability. Prius 10-15 (that's 5 years) has so many big problems... and I though I was ahead doing the entire egr/intake/OCC cleanup (a big job in itself).

 

not with 205k!
35k is a very different beast... and $20k for 2014 is insane when you could probably buy new for not that much more and not have gen3 issues...