Abstract: A computer implemented method for providing a diagnosis for automotive engine malfunctions using collected vehicle emissions data. The concentration levels of gases within exhaust emitted from a vehicle engine being determined and compared to a plurality of predetermined concentration level data sets stored in a database to find a matching data set. Each predetermined concentration level data set having corresponding engine diagnosis data for identifying engine malfunction. The engine diagnosis and concentration level data being printed on a testing diagnosis form to be filled out by mechanics upon repair of the malfunctioning engine. Upon return of a previously tested vehicle that has been repaired, the same test is performed on the vehicle and the newly collected concentration level data is compared with the prior failing concentration level data to determine the accuracy of the repair performed.