Greetings, my wife has a 2016 XC60 with a intermittent over heating issue. Drop the vehicle off at the radiator shop, and they replaced the oil cooler, water pump, and thermostat assembly. Also, flush coolant system. Condition was not corrected. They were at a lost for a remedy, so they towed the vehicle to a Volvo Dealers. The dealer guess it was a cylinder head leak but, no oil was found in the coolant reservoir, and want $11k to continue. Well, we found another shop specializing in European autos. They said they could help. First, they replace the oil cooler, then the water pump, and finally the thermostat asm. oh, and vacuum purged the coolant system.
Well after replacing every part the previous tech did the vehicle stills over heats intermittently. I mean sometimes it over heats and sometime it does. When it does over heat while driving it seam to go into some sort of limp mode declaring the temperature is to high in the message center, and slows the fuel feed to an idle. After turning off the vehicle and waiting 10 or so minutes, upon restarting the engine the temperature gauge reads normal. (poorly design gauge) It will allow you to drive on.
I was thinking it was some faulty sensor, but no codes to point the direction. Does anyone have a suggestion on where to look?

Also, the decision to have the second tech replace the new parts was on his recommendation that part may have been defective. May or may not have been true however, he was confident the HG wasn't the issue due to no hydrocarbons were found in the coolant. He said a test was performed three (3) times from the coolant reservoir. Secondly, he said the engine temperature was tested by hand held thermometer, and found the engine didn't exceed 180 degrees when the gauge read overheating. At this point we were thinking maybe it was electrical, a sensor. Maybe instrument cluster or something sending a fault reading to the temp gauge? Never the less it’s still occasionally overheating.