I have a 1997 Silverado 5.7L 4x4. It is throwing a permanent P0A00 code even after replacing the ECT sensor. You can clear the code and reset computer but it still read Permant P0A00 as soon as you scan with a scanner.

 

that doesn't appear to be a valid trouble code for your truck: https://charm.li/Chevy%20Truck/1997/...Code%20Charts/

Try a different scanner.

What does your temp gauge say?

 

The code stated P0A00 Motor electronics engine coolant temp. On multiple scanners. Ever if you clear all codes then it reads this code without ever cranking the vehicle and says permanent P0A00 code. I’ve replaced both ECT sensors one for PCM and the one for the gauge. I’ve checked all wires everything is fine. Temp reads fine in scanner but reads high on gauge. I drive the truck 1.5hrs to work and it never runs hot I never have to add water or anything.

 

 

From service manual
troubleshooting: Temperature Gage Indicates Hot:

https://charm.li/Chevy%20Truck/1997/...dicates%20Hot/