My check engine light came on today. My scangauge came up with a P128 code which translates into sensor reading lower than expected temp. The scangauge says my temp is 177 deg (usually is a little higher during normal operation). The instrument temp gauge is where it usually is. Is this an automatic sensor replacement? Does the 5-10 deg reading difference cause the CEL to come on? Has anyone had to replace their temp sensor yet? Car has 93K miles and is a 2002 S40.

Thanks

BTW reseting the CEL doesn't work as the same code keeps popping up.

Change the thermostat 177 is too cool, it is very sensitive to running at proper temp.