Hello all. I have a 2016 tahoe with the 5.3. The engine light came on and it was code P219b which is fuel air mix bank 2. Well thinking it was maybe carbon build up i put techron in the tank. The next day it went off. Then bout week later the light came back on, same code, then 2 days later light is off. But now ac blows hot air. I read that they have issues with the condenser. Could an ac leak have caused this code? Thanks for any responses.

 

No. A/C Blend door is probably stuck. There are already endless topics about that in the forum.

At least you know your engine problem is only in Bank 2. I would check the Bank 2 intake and exhaust for leaks.
https://www.obd-codes.com/p219b