On my 2003 D2, I often run high 190s on the highway, between 200 and about 208 city with my UltraGauge. (Similar to Scan Gauge II.) I ran the same temps before and after the new thermostat that was installed with new head gaskets.
I would expect any sensor errors would be apparent at startup temps. You might want to compare outside temp to the temp when you first start the engine. In the first few seconds after startup, your engine should be the same temp as the outside average for the previous few hours. Your external temp reading on your heating/cooling system should give you a good engine temp reading within the first few seconds of start up.
I would expect any sensor errors would be apparent at startup temps. You might want to compare outside temp to the temp when you first start the engine. In the first few seconds after startup, your engine should be the same temp as the outside average for the previous few hours. Your external temp reading on your heating/cooling system should give you a good engine temp reading within the first few seconds of start up.