My issues have been resolved: As I suspected (and as doc's has noted...) replacing the Temp. Sensor resolved the whacky/erratic gauge behavior. - the (old) thermostat looked/was ok - but since I had the area open to replace the temp sensor, I put in a new thermostat anyway. Cleared up my A/C for the...

I own a 2000 S40 - purchased new... it now has 165,000miles (USA) - still looks/runs good. Nonetheless, I would buy an S70 - the 70 is a bigger car and from what I've seen (over here) appear to be driven longer by their owners. If you decide on an S40, go for a more recent model (with slight improve...

I'm having a similar issue with my S40. The erratic temp gauge started shortly after my A/C stopped cooling. A/C needs to be recharged. Appears that the temp sensor or thermostat incorrectly signal an "overheat" condition through the computer and the car responds as if it were overheating....