Hopefully you nailed it with the sensor replacement. Did you actually actively clear the codes and reset the CEL after replacing the thermostat?

 

 

Either with a code reader with clearing capabilities, OR, you can disconnect the battery for 20 minutes to clear and reboot the car's computer system.
( disconnect the - negative terminal at the battery. Don't disconnect or touch the + positive terminal so as to avoid any shorting)

 

And don’t close the rear hatch door!! It’s a bear to reopen manually!!
Put a folded towel over the latch to prevent it from closing.

 

Replacing the thermostat might well have fixed the original issue, but not clearing the codes would have left the error until it was cleared, or after a certain number of drive cycles.