[Manitcor]

Subject: Intermittent Malfunction Indicator Lamp (MIL) and PCM DTC P1404 (Recalibrate PCM)


Models: 2001 Buick Century
2001 Chevrolet Impala, Malibu, Monte Carlo, Venture
2001 Oldsmobile Alero, Silhouette
2001 Pontiac Aztek, Grand Am, Grand Prix, Montana
with 3.1 L or 3.4 L Engine (VINs J, E -- RPOs LG8, LA1)


Condition:
Some customers may comment on the MIL illuminating intermittently with no other driveability concerns noted. Upon investigation, the technician may find a stored PCM Diagnostic Trouble Code (DTC) P1404.


Cause:
The EGR valve pintle position voltage may not correlate to anticipated PCM calibration values.


Correction:
Important: Make sure the TECH 2 has been updated with software version 21.000 (Released January 23, 2001), or greater before attempting this bulletin.
Prior to recalibrating the PCM, verify the following diagnostic values with a Tech 2 using the following steps.
In the Powertrain engine data menu, select F2 EGR Data. Press enter.
With key ON, engine OFF, view the EGR Position Sensor Percentage (%).
If the actual position is greater than 3.8 percent, and no other EGR codes or symptoms are present, then proceed to step 4. Otherwise, proceed to step 3.
If the actual EGR pintle percentage observed in step 1.2 is less than 3.8 percent, or if other EGR codes or symptoms are present, then proceed with published diagnostics found in the Service Information Manual. When the appropriate repairs are completed, proceed to step 4.
PCM calibrations to correct this issue have been released for service. Reprogram the PCM using Techline version 3.0, or greater, of the 2001 model year.


Calibration Information:
The Calibrations are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting March 2001, on the TIS 2000 version TIS 3.0/2001 data update or later.


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these 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 your GM dealer for information on whether your vehicle may benefit from the information.


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