Service light

I would say, as long as the light goes out and everything working find, why worry?
I have a 89 Turbo, the service light stays on a least three or four minute and everything is find, it even passed the emmision test, ok? :Wink:

Unless you have a Volvo dealer service your car, the service light will stay on for apprx 2-3minutes after you start it. There is a reset code, but as usual, Volvo will not tell you about this, you car is fine, as long as the light keeps going out after a few minutes
Gator

Have a look at this, I found it on internet and haven't tried it my self but it seems creadable.

Reset Volvo 850 XC70 S70 V70 C70 S80 Service Light
By Matt
850 (1993-1995)

There are two diagnostic units(it says A and B on the cover) located adjacent to washer reservoir under the hood.

1. Turn on the ignition and open the module A and insert the flylead into socket 7.
2. Press the button on the diagnostic unit 4 times, briefly but firmly.

Then the LED illuminates and stays illuminated, and the system is ready to accept manual code input. A code number for resetting the service reminder light is 1-5-1.

3. To do this, press the test button once and release it. And LED illuminates again.
4. Then press 5 times and wait for the LED to illuminate.
5. Press the button once and LED should flashes several times in succession and the reminder should have been reset.
6. Switch off the ignition and replace the flylead in its holder and close the cover.

850 (1996-1997) and S70 and V70 (1