CB23-L-001

IN SOME 2021MY ISUZU F-SERIES VEHICLES, OPERATORS MAY EXPERIENCE AN ILLUMINATED CHECK ENGINE MALFUNCTION INDICATOR LAMP (MIL) WITH DIAGNOSTIC TROUBLE CODE (DTC) P2201 NOX SENSOR CIRCUIT PERFORMANCE SENSOR 1 AND/OR DTC P20EE DIESEL EXHAUST FLUID (DEF) SYSTEM NOX TRAP LOW EFFICIENCY SET IN THE DEF CONTROL UNIT (DCU). WE HAVE DETERMINED A DCU CALIBRATION ERROR IS CAUSING THIS DTC TO SET. THEREFORE, THIS DTC MAY BE RESOLVED BY REPROGRAMMING THE DCU WITH A REVISED CALIBRATION.