Do Check Engine Light Codes get Stored in ECM if the check Engine Light turns off on it's own?

I have a 2010 corolla with 166k miles on it. I have never had any major issues with the car. This past Saturday I drove about 300 miles and just as I was about to get home I got 3 lights that turned on on my dash: Check Engine Light, vsc, and traction control off. All 3 lit up at the same time. I did not notice any difference in the driving of the car, it changed gears, accelerated, broke etc… all normal. Using an OBD II scan tool I go the code p2757. P2757 is: Torque Converter Clutch Pressure Control Solenoid Ctrl Circuit Performance or Stuck Off. I let my car sit over night and today I turn my car on and the 3 lights have turned off. I make an appt to take it to Toyota in a couple of days but now that the light is off, will the Toyota techs still be able to pull up the code that appeared when the lights were on?

I DID NOT reset the battery as some folks do, I merely turned my car on like usual and the lights were gone.

1. So will the techs be able to pull up the code to diagnose the real issue?

2. Is it possible there is no issue with the car since the lights turned off on their own?

3. My car is due for emissions testing soon, will my car pass emissions now that the light is off or will it fail because the emissions testing station will find codes in the ECM’s memory?

Thank you all in advance.