2007 Volvo S80 reset the "book time for maintenance" message
1. With your foot off of the brake.....Put the key fob all the way into the dash slot
(until it clicks-locks in place)
2. With your foot off of the brake, tap the engine start button - this should
light up a portion of the gauges.
3. Push down the trip mileage counter reset button (a nub to the right of the
RPM gauge)
4. Still holding down the trip mileage counter reset button, and with your foot
off of the brake, push the engine start button for about 2 seconds until all of
the informational lights (i.e. check engine, etc) light up. Once they light up,
you can stop pushing the engine start button (but continue to hold down the trip
mileage counter reset button).
5. After a couple more seconds of holding down the trip mileage counter reset
button, you will note that the "i" (the alert that there is a vehicle message)
will begin to blink. This is your cue to release the trip mileage counter reset
button. You must do this before the "i" stops blinking, or it will not reset.
6. Restart the car to confirm that you have successfully reset the "book time
for maintenance" message
This is the procedure I use, but credit belongs to someone else at: