In Use Performance of Catalytic Converters on Properly Maintained High Mileage Vehicles

A test program to evaluate the performance of catalytic converters from fifty-six 1981 and 1982 model year high mileage properly maintained in-use vehicles (from 21 engine families) was performed by the Certification Division of the Office of Mobile Sources (EPA). The program is called the Catalyst Change Program. All program vehicles were screened for proper maintenance and for mileages that ranged from 35,000 to 60,000 miles.

Among vehicles belonging to 21 high sales volume and high technology engine and emission control system designs tested, poor catalyst performance was determined to be a significant contributor to emissions failure of properly-maintained vehicles at or near their warranted useful life mileage.