Having been on the having all of the valves replaced and the head of the motor repaired, I can tell you that most cars need timing belts around 100,000 miles. Try not to skip that service. Any mechanic can hook the car to the "computer" and tell you why it came on to begin with and reset it if it was something stupid.....all for free. But if it was the timing thing, it costs WAY more to fix it if it fails than to have the preventitive maintenance done....from someone that knows first hand.