Here you are..... you need the solenoid pack for the transmission. That code,p0795, says that solenoid "C" in that pack is bad or the circut it bad....95% it is the solenoid pack. This is inside the trans with the valve body.
P/N XW4Z-7G391-AC (sometimes called a module) list is $377.76 and your cost is $203.99. Could this be the "module" your tech was referring to??? not the engine module like you thought??? During your "tune up" could you have disturbed the transmission harness somehow??
The valve is $259.24 and your cost is 168.51. I can have the module tomorrow if you want it and the heater valve is in stock now.
Max