Emission warning light is on on 2000 Ford F-350 Super Duty

The emission warning light came on the other day and I am looking for ideas as to what the cause may be

The emission warning light, or Check Engine Light, can come on for a number of reasons. If there is a problem with the measurements made by any of the many sensors that monitor the emissions of your vehicle, the light will come on. There is at least one trouble code that your engine computer has recorded that is causing that light to come on, and you now should track down a good diagnostic technician who can figure out what the root cause of the problem is. There's more information here: