P0AA6 and C1310

Ok. So I've pretty much read all of the threads on these codes at this point.

I had a blown head gasket. And there was significant coolant in cylinder 2, so much so that I was getting really bad misfires on startup.

On one rough startup, I got the p0aa6 and c1310 codes and the car turned off. I wrote down the codes, cleared them, restarted the car and they didn't come back on and everything was fine. When I looked the codes up afterwards I realized that the detail codes were important.

Used Kseal and the head gasket leak is fixed. Fast forward 2 weeks, and the codes reappeared on startup. I got a detail code of 526 and cleared them again.

Realized that I need the 2nd code afterwards.

So here's my issue. The code is so intermittent. So until the code reappears and I can get the 600 code, is there anything that jumps out at anyone that I can check without the meg?

And being it is so intermittent, how will I know it is even repaired?

Summary: Here's what I know...

-Codes appear only on startup.
-Codes initially started after rough misfire.
-Coolant overflow tank was overflowing frequently from bad head gasket and coolant frequently got splashed around front of engine from various drain, refill, gushing out radiator neck, overflow tank, etc.
-Battery meter is looking normal while driving. Also, my MPG is higher than normal (averaging around 53mpg, where it has usually been around 47)
-From what I've read, this is most looking like a 614 code as there is no issue while shifting or the air conditioning.

Hoping to start troubleshooting before the code pops up again.