Car overheating when Idle

my suspicion is that the head gasket is bad . Is the exhaust white , Is there goop under the oil fill cap ? A compression test will tell

No goop whatsoever, looks very clean. Oil level is fine as well.

I had the same problem on my 2009 Mazda 6. It was due to a faulty cooling fan control module. It actually eventually caused my car to overheat and destroy my engine. You should get it checked out ASAP. There is a technical service bulletin released by Mazda about this issue. Unfortunately my dealership ignored this bulletin and my car, and my wallet, suffered because of this. Also if you have this issue PLEASE REPORT this to the NHTSA. If enough reports are made it increases the chance of a recall, which would help protect consumers and owners like us and allow reimbursement. https://www.nhtsa.gov/recalls

I have a 2009 mazda 6 v6 3.7L my radiator fans do NOT turn off, but my car starts to over heat at idle/traffic. A/c air becomes warm air As soon as i start driving it goes back to normal and a/c air is cold again. Changed thermostat, also did radiator flush. Also change my oil and never see any coolant in oil. And no missing coolant . Still havent found the problem.

My 2010 Mazda 6 3.7 liter dies the same thing too. Don’t really know but it had no problem regarding overheating in the winter. It just whenever the environment start to get warmer, the temperature gauge start acting up. Did a pressure test on coolant, no leak, then flush out my coolant and my car have heat and ac blow cold but at idle and only in traffic where it’s hot then it started acting up and about the same time, my ac start blowing not do cold air, more like warm air. Fan blow as well so I’m thinking maybe it might be control fan module and if not then might be the radiator itself. I doubt it’s the fan because I change it 2 year ago for a brand new oem one. But yeah still haven’t figure it out too.

Water pump.

Did you ever find the fix for this? I have a 2010 Mazda 6 v6 with the same issue. My shop told me it's the control module, but that this car doesn't have a separate control module. $600 to remove/replace the entire cooling fan unit...

Same issue on 2009 3.7l V6 engine. Fans do not come on, but when I power them directly they work, so I know they are good. I am not spending $600 for the fan assembly kit, but have chosen to try an aftermarket electric fan control kit from Hayden. https://www.haydenauto.com/en/ecatalog?year=2009 I may get brave and try to wire it directly to the Mazda temperature sensor instead of the one supplied with the kit.