The previous (second) owner of my '98 S90 didn't know whether the car has keyless remote entry.
Do all S90s have it, or is there some way to tell from the VIN?
Thanks

I called our local Volvo dealer and from the VIN they told me that my 97 V90 came with one, the stock price for replacement was around 150.00

YES - definitely has keyless entry. Both previous replies to your post correct, and to add to the last one (fasteddy) - when you do get replacement Volvo keyless remote and new batteries (it will take 2 dime sized chip batteries)... do as fasteddy stated, and : (1) enter car, lock doors, put key in ignition (2) turn key quarter turn (like fasteddy said, position 1 to 2 (3) then do this SIX times in rapid secession. On the 6th quick turn, leave key in position 2 - push lock button on the remote. This will set/initialize your keyless. You can "monitor" this by watching your red security button for the car's system - located on the dashboard, right passenger side. The red light normally will just blink periodically. When you have pressed the remote button, this red light will remain lit afew seconds as the signal is transmitted to your remote for initialization purposes. After you do this, all should work well!

Yes...at least mine does and it's a garden variety S90.

If the P.O. seems not to know it's probably because he has lost - or never had - the remote transmitter. You may find one on eBay, but it will need to be programmed to the car. Others here (or dealer) may know how to do this.

With fresh batteries, my remote will work through a house window with the car 20-30 ft away outside in the driveway.
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Bob: Son's XC70, my 83 240, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles

yes it does if its an s90

pick one up on ebay,install fresh batteries, to program cycle the key from position 1 and 2,press the lock button on the remote while on pos 2 release and turn to pos 1 repeat about 5 times
think it should work after 3 cycles