A novel real-time OBD output parameter-based commercial fleet maintenance alert system performs an automated and intelligent analysis of each vehicle's OBD and vehicle sensor output parameters in real time during the operation of the vehicle to determine and alert each fleet vehicle's maintenance needs to an electronic device utilized by a driver or a commercial fleet operator. The commercial fleet maintenance alert system is also capable of performing a machine-level pattern analysis to correlate a previously-alerted maintenance need of a particular vehicle with a subsequent breakdown of the particular vehicle in a commercial fleet to predict a future probability of similar breakdowns by other vehicles in the commercial fleet. In addition, the commercial fleet maintenance alert system is able to generate maintenance status reports and estimate maintenance costs for machine-identified vehicle maintenance needs, which is then compared against actual maintenance costs to improve the accuracy of future cost estimations.