See Figures 1, 2 and 3
After the required replacement service is performed on the oxygen sensor system, the service light in the dashboard may be reset. Remove the cover from the special odometer under the dashboard and depress the white button. This will reset the counter for the next 30,000 mile (48,309 km) segment. Not all models have oxygen sensor service lights.
Many Volvos, particularly the 700 series, have a service reminder light on the dashboard. When the elapsed mileage has reached 5000 miles (8052 km) since the last oil change, the light will come on for two minutes each time the engine is started. After changing the oil and filter and performing the other necessary safety checks, the reminder light may be reset by the following procedures.
On 740 and 780 models, the reset knob is found on the back of the instrument panel. Pressing the knob resets the counter for another 5000 mile (8052 km) increment. Use care in reaching behind the instrument cluster-don't pull any wires loose or disturb other components.
On the 760 model, remove the rubber grommet on the front of the instrument panel. This exposes the head of the reset button within the dash. Use a small screwdriver to depress the knob and reset the counter. Use care not to scratch the face of the dashboard when removing or installing the grommet.