truck threw P0116, where to start??

Okay, my ultra gauge just threw a P0116. A google search says that it is the coolant temperature sensor. The ultra gauge is showing a steady 192.

Is the gauge getting the reading from the sensor?
If so, since there is trouble with it, is it accurate?

Where do I start? Replace the sensor immediately? Is aftermarket okay?

Background:

When I got the truck it had green coolant and was running 10 degrees hot. The reading on the ultra gauge was a little erratic too, umping between 199 and 204 degrees. I read up on the forums and found that the jiggle valve on the t-stat is supposed to be down, not up, and that if it's up you can get a 10 degree difference. I flushed the coolant, put in red, put in a new t-stat with the jiggle valve down, and changed the fan clutch. It was immediately 10 degrees cooler, and has been for 1.5 weeks. Now I have this code.

 

Toyota nation says:

P0116 Engine Coolant Temperature Circuit Range/Performance Problem

Is that actually the sensor?

 

2nd gen ?
The book says check for other codes.If no go to next line.If yes trace other codes.
remove thermostat and inspect it 176 to 183.(put it in a pan on the stove with a thermometer in it )
confirm it opens and closes completely.if it works right go to the next line if not replace it.
lastly replace ect sensor if the thermostat is working and installed properly.

 

I think you installed your t-stat wrong.Not sure if this pic is allowed.

 

I'm pretty sure it's in the right way. Check out this thread:

http://www.tacomaworld.com/forum/1st-gen-tacomas/311830-thermostat-jiggle-valve-3-4l-6-cyl-trd.html

In particular the third post has a pic from the FSM. The 5vz-fe is different from the 4bangers, and despite the lack of logic, the jiggle valve is supposed to be down.

 

Mine's a 1st gen. 2003. 3.4L

 

More info:

My wife was driving the car when it threw the code. The PO installed an ignition kill device. If you don't know how to disengage it, the truck will crank endlessly but not start.

My wife forgot to disengage it and let it crank for a little bit before she remembered. When she remembered and finally started the truck, the ABS light was on. This had happened once before, so she shut the car off and started it again and the light was gone. A few blocks down the road it threw the P0116 code.

So now, I'm guessing it's just an error triggered by the ignition kill device, or worse, the ignition kill device fried the sensor.

I'm going to clear the code and see if it comes back. I bought the sensor just in case, but it was $29 bucks and doesn't look so fun to replace.

 

Well, I've put about 130 miles on it and the code hasn't come back yet.

 

That explains why you have an ignition kill....you live in Oakland, lol. I used to live in San Jose.

 

Yeah, you get it then. And if they're not trying to get the whole truck, they're under it hacking off your cat converter.