MIL ON AFTER LONG DECEL., DTC P0401 SET (EGR FLOW). Chevrolet Lumina 1996

SUBJECT: MIL ON AFTER LONG DECELERATION, DTC P0401 SET (EGR FLOW) (REFLASH PCM)

MODELS: 1996 BUICK REGAL 1996 CHEVROLET LUMINA, MONTE CARLO 1996 OLDSMOBILE CUTLASS SUPREME 1996 PONTIAC GRAND PRIX WITH 3100 V6 ENGINE (VIN M--RPO L82)

CONDITION:

SOME OWNERS MAY EXPERIENCE A MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATING ON THE VEHICLE'S INSTRUMENT PANEL AFTER A LONG DECELERATION WITH THE TRANSMISSION TYPICALLY IN THE OVERDRIVE POSITION. A DIAGNOSTIC TROUBLE CODE (DTC) P0401 IS STORED IN THE POWERTRAIN CONTROL MODULE.

CAUSE:

THE EXHAUST GAS RECIRCULATION VALVE (EGR) DIAGNOSTIC, P0401 EGR FLOW, MAY HAVE FAILED THE SELF TEST BECAUSE THE EXPECTED CHANGE IN MANIFOLD PRESSURE (KPA), AS DISPLAYED BY THE MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR, FALLS OUTSIDE THE CALIBRATED WINDOW.

CORRECTION:

A NEW FLASH PROM CALIBRATION IS RELEASED TO CORRECT THIS CONDITION. CHANGES ARE MADE IN THE FOLLOWING AREAS OF THE DIAGNOSTIC PORTION OF THE CALIBRATION:

1) ENABLING CRITERIA FOR THE DIAGNOSTIC TO RUN. 2) EGR CONTROL POSITION DURING THE DIAGNOSTIC. 3) EXPECTED MAP CHANGE DURING THE DIAGNOSTIC.

THESE CHANGES ARE BEING MADE TO PREVENT FALSE DTC P0401 CODES FROM SETTING.

CALIBRATION INFORMATION:

THE NEW CALIBRATIONS ARE AVAILABLE FROM THE GM SERVICE TECHNOLOGY GROUP STARTING WITH CD NUMBER 15 FOR 1998.

IMPORTANT: DO NOT ATTEMPT TO ORDER THE CALIBRATIONS FROM GMSPO. THE CALIBRATIONS ARE PROGRAMMED INTO THE VEHICLE'S PCM VIA A TECHLINE TOOL DEVICE.

CALIBRATION CARLINE/AXLE EMISSIONS NUMBER

09365714 ALL W WITH 3.33 AXLE UNLEADED EXPORT/CANADIAN 09365704 ALL W WITH 3.33 AXLE USA NATIONWIDE 09365694 CHEV W WITH 3.33 AXLE USA NATIONWIDE POLICE PKG. 09365724 CHEV W WITH 3.33 AXLE UNLEADED EXPORT/CANADIAN POLICE PKG.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION LABOR OPERATION NUMBER DESCRIPTION TIME --------------- ----------- ----------------

J6355 ON-CAR PROM REPROGRAMMING USE PUBLISHED LABOR FLASH E PROM OPERATION TIME

FIGURES: 0 ATTACHMENTS: 0

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.