Truck Repair: 2000 Dodge Dakota, vacuum system, dodge dakota

Question
What is the most common cause, for 'check engine' light to come on? checked all fluids, oil, transmission fluid etc: Does'nt seem to be any noticable decline in truck's performance, thank you.

Answer
The most common reason for an engine light to come on are related to the emissons system, mainly all sensors that have to give the ecm an input like o2 sensor or fuel vapor recovery system. beleive it or not, the main reason for most engine lights to come on is a faulty, loose or missing gas cap. the vapor evac system does a continuos vacuum system check and logs a code when it fails the test.