There are hundreds of reasons why a Ford Windstar's check engine light comes on, but according to AAMCO, problems with the mass air flow sensor are one of the most common. This problem usually does not cause serious problems with drivability but can decrease the vehicle's power and cause sluggish reactions. Mechanics connect a device that checks for diagnostic codes stored in the vehicle's on-board computer.
Sometimes an oxygen sensor detects that the fuel mix is too rich, causing the light to illuminate. This condition often causes misfires and affects fuel economy. Having it repaired quickly reduces the vehicle's pollutants and decreases the chances of damaging the catalytic converter.
Bad spark plugs or wires, ignition coils and vacuum leaks cause cylinder misfires. The on-board computer stores a P0300 code to indicate random misfires, and the light warns the driver of a potential problem. These problems also cause damage to the catalytic converter.
Modern vehicles recirculate exhaust gas through the combustion chamber to reduce nitrous oxide and keep the chamber at the optimal temperature. Insufficient EGR flow is another reason the driver may see the light.
Another oxygen sensor senses problems with catalytic converter efficiency. Most drivers do not notice this problem unless the light warns them about it. An auto repair shop uses the stored code to trace the problem and makes repairs that ensure the vehicle continues operating with low emissions.