P0869 = Line Pressure High
P0732 = Gear Ratio Error in 2nd
Sounds like you have two different issues going on. The Line Pressure High code usually results from a bad LP sensor (giving too high a reading). If your line pressure is actually
too high, that would likely be due to a problem with the line pressure control circuit (wiring or solenoid) or a stuck main regulator valve. Usually, if the reg valve is stuck, you get LOW pressure, not high, so I would discount the stuck valve.
Your dealer can read your line pressure (from the sensor) using a scan tool. He can also use a special adapter tool to tee in a mechanical pressure gauge (while your LP sensor is still hooked up), allowing him to confirm whether the sensor reading is accurate. So I would confirm the sensor is OK, and if so, then check the wiring (for the LP control circuit), and if OK then probably replace the solenoid assy (inside the trans).
Your other issue is the gear ratio error. If your PCM detects trans slippage, it will go into a mode called "logical limp-in", where it will shift from 1st gear directly to 4th. It will then remain in 4th until you come to a stop (or very slow speed), at which point it will go back to 1st. It will continue to shift between 1st and 4th (only) until you restart it. If Autozone found a P0732 code, then you likely have a cut or torn 2C clutch piston seal. The seal lips are bonded to the 2C clutch piston, so you probably need a new piston (52119655AA, $44.45 list from Mopar). Unfortunately, you have to pull the trans and tear it halfway down to get to this piston. Fortunately, you should still be under warranty!
If you drop the oil pan and valve body assy, you can air check the 2C clutch. The 2C, 4C, and LR clutches are all applied directly from the valve body, so if you pull the VB
you can blow shop air into the clutch apply ports (about 30 psi) and see whether you get a big leak or not. These clutches all have a small bleed orifice, so you will get a little
bit of air leakage, but nothing blatant. So if you need to replace the solenoid (for the high LP issue), you could air check the 2C clutch while you're in there.