[Abalek]

Hi I have a 2016 optima. The other day I was driving down the road at 65mph and I lost engine power and breaks.
I don't remember if I lost power steering or not I was trying not to crash the car with my kid in it.
Once I was able to coast to a stop I put a code reader on it and had 18 codes that popped up. I'll try to post that. After getting it home I started looking threw stuff trying to figure it out. I checked all of the fuses, relays. Cleaned all of the grounds, inspected wires, got the battery tested all came back fine. I tried leaving the battery unplugged and computers unplugged for a few hours.
I watched a YouTube video talking about wires with the starter getting hot and could cause a short so I disassembled everything and got to the starter which everything looked good. I decided to take the starter off and take to the local parts store for them to test it which came back bad. I'm having a hard time believing that a bad starter would make me loose engine power and breaks.
Currently the breaks are extremely stiff, does not want to start you can turn on the car you can hear the fuel pump when you push again to start you hear the relay click but nothing. There are 3 codes now
b1112 which says battery/ignition voltage to low
B2502 and b2500 both say they are for the air bag and talk about a short with battery/ bulb/ground.
Has anyone had this kind of issue? Could a bad starter really cause all of this? How do you go about looking for a short with air bags?
I'm pretty fed up with this car the first year was great but after the derecho we had it has had problems after problems.

 

[Abalek]

Turns out the motor seized. I was able to turn it by hand so I didn't think it was that. I had a shop look at it and said it was seized. I took it to the dealer that had it 3 weeks before my issues for the knock sensor warning light. All they did for that was download an update. Now with it seized they are replacing the motor under warranty. My question is what all comes on the motor? Is it just a short block or something where they take everything off of my old engine and put it on the new one? The starter is bad but I have a new one in the back seat. They are trying to sell me a starter/labor to put one on. New engine coolant, transmission oil and new belts and hoses for $1400. I feel like the coolant is something that they should have to replace when switching the motor...the other stuff idk how it works. New engine have all the stuff on it needs or they have to take all the old stuff off the bad engine and put it on the new?