Sorry for late reply. I have not changed my thermostat yet. The P06DD code has gone away on its own. The code was being set due to oil pressure after start remaining higher than usual. Sometimes the pressure would return to normal (no code set after I cleared it) and would not return. Sometimes I had to stop and turn engine off then restart and pressure would return to normal with no code set. I’m guessing something got unstuck. Good luck and keep us posted!