Got a p0116 code today

[FriboRage]

I drove to lunch for work todanon my 08, no problems, raining pretty hard. Started it to go back to work and I get on my DIC "charging system failure" "service vehicle soon" (no dtc's) Shut it off for about 5 minutes, started it again to get back to work, then shut it off again at work... Disconnected the battery and reconnected it (had this problem before and this fixes it).
However, this time when I started it, there was no more "charging system failure", normal dic but I noticed my temp gauge was down to 0 like it was a cold start (just got back from a 20 minute drive). I also had hot air from the heat. I shut if off, disconnected and reconnected the battery again, same thing except this time I had a p0116, Engine Coolant Temperature (ECT) Circuit Range/Performance Problem

Any ideas? This happened very suddenly.

[OH4CompG]

Inspect the wires goin to your engine coolant temp sensor under the thermostat on the intake manifold. Make sure they didn't come too close to the exhaust crossover and get melted

[FriboRage]

Yeah, I looked at the wires, they're definitely intact and fine... I disconnected the plug for it and reconnected it, made sure it was all dry... made sure my pcm connectors were all dry and reconnected them, reconnected the battery again.. same thing, except when I started it this time it idled really high, like 2k for a few seconds before it settled down to 1k, and then down to like 700 where it normally is. (Maybe just from the battery and pcm being unplugged?) Ugh, I've got a trip on saturday and this is pissing me off. I borrowed the obdII scanner from work to keep an eye on my coolant temps... the temps are displaying, so does that mean the coolant temp sensor is functioning? Is it a different sensor that operates the guage?

Just seems connected to me that I had this electrical problem "charging system failure", the guage was still working, then I unplugged and reconnected the battery and suddenly no guage... all other gauges are fine

[FriboRage]

Also cooling fans are on high full time.

[BillBoost37]

If you see it with the scanner, then the pcm is seeing that temp. The gauge on the dash is fed seperately. Our ECT sensors have two sensors built into one.

check gearchatter for the info on that code. It'll likely help.

[FriboRage]

Well I went to bed last night with the problem still going on, just sat all night and today it was better, I started it and no cooling fans, gauge started to creep up so I was happy. Thanks for your input, guys.

Wish I knew what causes these weird little intermittant gremlin issues