Sunday night, my 99 V70 T5M suddenly developed a hard starting when hot problem. No codes, no check engine light. Yesterday, the Check Engine light came on, with the P0116 (coolant temperature sensor code).

I see that replacement sensors are made by Airtex, part number 5S1588, available from Rock Auto (.com) and from KEM, part number 140-831. The problem with the Airtex one is that they list the same part number for 98 and 99-2001, and Volvo has a separate number for 1998, and this makes me nervous. The KEM part number is specific to 99-01, so I would be willing to use it, but I can't find any place that carries KEM. Does anybody know of a source for it? (Has anybody used the Airtex part on a 99-01 car with no problem?)

Why don't I just buy the Volvo part? I probably will, given the time constraints, but as a rule, if an original part has a reputation for failure (like the Volvo coolant temperature sensor), I am inclined to try another brand. Especially for less money.