Had an overheating problem. Water pump bad, replaced. Month later car overheats again. Took it to water pump repair shop. "the car's not really overheating it just thinks it is". Sensors replaced. 2 weeks later, happened again, cooling fan starts, gauge pegs, warning light, warning bell, limp mode. Car not overheated. Waited 2 hrs, car starts up and drives fine. Coolant sensor replaced again. Went to 2nd shop, both reputable, 4 hours of analysis. "We can't find the problem, you need to go to the dealer, possible pcm". Heating and cooling function just fine. Car thinks it's overheating, moves to protect engine, shuts it down, waits for engine to "cool down" and then works fine for about another 30 min or 20 miles. PCM? If so, obsolete at dealer. Suggestions? Including son's 05 V8, this is my 4th LS, 2000 V8, 2002 V6, 2005 V6 and son's 2005 V8. Love them but baffled at this one.