2002 C5 Temperature Gauge Reads Hot Even When Cold

[8kgold69]

I have a 2002 C5 with 60,500 miles. Well maintained, when I initially start the engine temp gauge goes to 260 and stays there, whether the engine is cold or warm. However the the hoses are cool, motor does not make any noise, the oil has no contamination, it is not over heating. I did change the temp senor on the left side of the block under the alternator. hoping this was the issue, but NO change. I checked all the fuses, all are operating. Any suggestions? Other test I should perform?
Thanks