Mine failed under the original warranty, I recall that the latch was replaced (the switch is internal to the latch) and that the part wasn't cheap.

Considering that the other 4 doors on the car don't have "door ajar" warning lights, have you considered just bypassing the switch, rather than replacing it?

-BTC

'98 V70 T5 5-speed, 167k mi, front IPD stabilizer bar, rear factory HD bar, Bilstein HD, Volvo strut tower brace and skidplate, e-codes, XC grill, Lidatek LE30, V-1, Mobil-1 since new

"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." -- Douglas Noel Adams (1952-2001)