Went to a meeting last night, and my Android radio head (which is tethered to a Bluetooth OBD) displayed temps that didn't make sense.

Normal temp is 185°, though it's not unusual for it to push 195 if really accelerating hard or pulling a heavy load with the AC on. But it topped out at 218, then dropped to 176 within a minute with normal stop-n-go city driving. In fact, it actually did the opposite of what I expected sometimes. For instance, accelerating from a stop caused the temp to go down, then go back up to 190 or 195 when driving around 35-40MPH with no air on. As soon as I turned the AC on, it would jump to over 200 in a few seconds. So I left the AC off.

The fluctuations are far too fast to be considered reliable. 10-15 degrees in just as many seconds in some cases.

I force-stopped the app I was using, but no change. The factory gauge didn't move at all during all this.

I thought maybe I was low on coolant, so I pulled over and cracked the radiator cap. It was almost 'cool' enough to keep my hand on it, but got the expected spurt.

Thinking it might be an electronics issue, I pulled the negative battery cable when I got home and let it set overnight. This morning, I did add a couple cups of antifreeze, but that's nothing earth-shattering.

So short of thinking there an issue with either the app in the radio head or the bluetooth OBD reader, could it be something else... such as the temp sensor that feeds the computer has gone bonkers? Something in the computer? Aliens?

 

Well, it's not my aftermarket radio. My mechanic hooked up his OBD reader and it was showing temp fluctuations as well. So it's back tomorrow for a new temp sensor and stat. Hopefully that solves the issue.