I have a 2005 Silverado with a block heater. Every time I plug the heater in during extreme cold weather I end up getting a check engine light because the temp sensor stops working. Is it possible the block heater is overheating the sensor? Right now the gauge on the dash does not register a temp when driving. Yes the engine is up to normal operating temp. This is second time this has happened. Do I need to move the sensor to the opposite head an extend the wiring.

 

Typical Phillips and Temro core plug heater? or one with the built in pump that is inline with heater core?

In any event, they do not have enough BTUs to overheat anything. The core plug element is about 250 watts and the inline pump unit is about 700 watts. Way less than 1hp of heat. Most likely the programmers at GM were asleep and didn't think about block heaters and the ECU is freaking out

 

It's just the standard brass GM thread -in block heater. It's just weird that I lose the sensor. It was working fine when I started the truck in the morning then on my way home I didn't have any water temp and the check engine light came on. thank you for your reply

 

Check and or replace the two pin coolant temp sensor connector/ pigtail.

Assure that the coolant temp sensor has the correct resistance/per temperature. Such chart is easily available with a search. I find GROK helpful in such matters. You can easily replace the sensor with a known good USED sensor from a junk engine.

I have 5 GMT800 in my daly fleet rotation, all are 20+ years old, using original sensors, no failures noted except mechanical ( physical breakage) during a header installation.. I habitually use engine block heater for 2 or 3 hours before morning starts for half the year ( Alaska winters) and have NEVER seen the symptom you have described.

ALL of which is the long way of saying : CHECK YOUR WIRING and Connections.