2012 Infiniti G37 I've owned since new. Ambient temp sensor was always super accurate. About a month ago it started creeping up 20 or so degrees above actual temp especially when in stop and go traffic. The sensor is just in front of the rad so I'm sure it's catching some heat from that but why didn't it do this for the first 7 years ive owned it? did i loose some insulation that used to be there? looking at the specs it looks like the temp isn't supposed to adjust if the vehicle speed is under 20mph.. why is mine adjusting all of a sudden The rad fan and condenser fans are working but I'm wondering if they are getting tired with age and not pushing as much air? raising the temp in the radiator and also not pulling enough outside air across the ambient sensor? The car isn't overheating but temps look a little higher than what I remember years ago So, programming issue? sensor issue? cooling system issue? just curious where to look first
Check the fans with the car hot and cold , just start car and put ac on and both fans should be full on high . Those fans are known to fail and Nissan or any aluminum headed engine likes to overheat . tThe ambient temp sensor , look at the sensor and make sure nothing has hit it or pushed against the radiator. Sensor could need replacing . Maybe an ohm spec available to test sensor or replace it with a factory part or known good part if no value is available for testing . I try and stay away from aftermarket sensors .
Thanks, at least confirms I'm on the right track to start diagnosing. Per obd the highest water temp I see in Florida summer bumper to bumper traffic is 205. Not terrible but I don't seem to recall it ever getting above 199
First thing I'd do is look at the ambient temp sensor. Make sure it is clean, and clean the contacts. There may be some corrosion increasing the resistance. Find the resistance chart for that sensor and check it at a known temp. Make sure the radiators are clean. If you have a U-pick it place nearby, you could probably find a used sensor for $5. But if new ones are only $10-20 at the parts store, I'd probably just get a new one. Also, if you have a good OBDII reader, set it up to look at the ambient temp and compare to the dash display. You mention the water temp being hotter than normal by a few degrees. That could be so many things, not going to get into that one here.
I run OEM mix.. The more I think about it I'm leaning towards the fans getting tired and not running at the rpm they did. That would explain the slightly higher coolant temps and cause a lack of fresh airflow over the ambient sensor.
Those fans aren't doing shit while you're in motion. If your issue is only at idle, they may be worth looking into, but if your water temps and/or ambient temp is higher while moving, it ain't the fans. Those fans pull a fraction of what air is being rammed through the radiator at 60mph.
