LTB00840NAS1

"SITUATION: ON VEHICLES FITTED WITH THE 4.2L SC V8 ENGINE ONLY, THE ENGINE MALFUNCTION INDICATOR LAMP (MIL) MAY BE ILLUMINATED. UPON DIAGNOSIS, THE TECHNICIAN FINDS THAT DIAGNOSTIC TROUBLE CODE P0420 AND/OR P0430 ONLY ARE STORED IN THE ENGINE CONTROL MODULE (ECM). CAUSE: THIS MAY BE CAUSED BY THE ECM DIAGNOSTIC SOFTWARE INCORRECTLY REPORTING AN AGED/LOW EFFICIENCY CATALYTIC CONVERTER."