Coolant Sensors and Temp Gage

The temperature gage on my 2004 Tacoma 2.7 ,4 cylinder goes all the way to hot quickly shortly after crank ups on cold mornings. after a few miles it returns to normal. The engine does not overheat. I have replaced the 2 coolant temp sensors, the 1 pin 20040 and the 2 pin 35010. I was told that the problem was either of the 2 sensors/ senders. The problem is still there. I am a novice mechanic at best. Could someone please give me some advice and / or a remedy for this.

 

By monitoring your temps via OBDII, what are your readings?

I ask because unless they changed it for an '04, the gauge on your dash is a simple dummy gauge and uses a sender that is independent from that of the sensor.

The actual sensor used by your PCM to determine when your engine is cold/warm/hot will also relay data via OBDII.

 

My first thought is a sticking thermostat. How soon after startup does the temp gauge spike? A couple minutes or right away?

 

The dash temp gage spikes from total cold to total hot about 5 to 8 miles after starting. It will only do this when night time outside temp is below 40.

 

I would replace the thermostat.