DTC P1404 EGR Closed Position Performance
That is most likely a false code cause by a programming error in the PCM.
There is a TSB on the subject. You will need to take it to the dealer so a new program can be downloaded to your PCM to correct the problem.
Here's the TSB
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 01-06-04-018A
Date: September, 2002
Subject: Intermittent Malfunction Indicator Lamp (MIL) and PCM DTC P1404 (Recalibrate PCM)
Models:2001 Buick Century2001 Chevrolet Impala, Malibu, Monte Carlo, Venture2001 Oldsmobile Alero, Silhouette2001 Pontiac Aztek, Grand Am, Grand Prix, Montana with 3.1 L or 3.4 L Engine (VINs J, E -- RPOs LG8, LA1)
This bulletin is being revised to update the calibration information to the latest available.
Please discard Corporate Bulletin Number 01-06-04-018 (Section 06-Engine).
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.
The EGR valve pintle position voltage may not correlate to anticipated PCM calibration values.
Important: Verify that the TECH2(R) has been updated with software version 21.000 (Released January 23, 2001), or greater before attempting the procedures in this bulletin.
1. <>Prior to recalibrating the PCM, verify the following diagnostic values with a Tech2(R) using the following steps:
The calibrations listed are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline(R) starting January 2002, on the TIS 2000 version TIS 01/2002 data update or later.