(TDI Clean Diesel I/M (Inspection Maintenance) Testing Issues due to Readiness Not Set):
Some readiness codes on TDI clean diesel vehicles require special driving conditions to be set. If DTCs have been recently erased from the vehicle?s ECM, it may take additional driving under different conditions to fully set OBD readiness parameters.
MVB 89 (on non-UDS protocol ECM?s) will store correct data concerning OBD readiness. This document illustrates how to manually read OBD readiness codes.