OBD - System improvements
File In Section: 6E - Engine Fuel & EmissionBulletin No.: 87-65-20
Date: June, 1998
OBD SOFTWARE UPGRADE
Subject:
On-Board Diagnostic (OBD) System Improvements
(Re-flash Calibration)
Models:
1997 Buick LeSabre, Riviera
1997 Oldsmobile Eighty Eight
1997 Pontiac Bonneville
with 3800 Engine (VIN K - RPO L36)
Affected Models Built After May 15, 1997
Affected Models Built Prior to May 15, 1997 and Have Been Subsequently
Reflashed in the Field
Affected Models with Bulletin 77-71-55A Performed
Does Not Include Pull Ahead Buick LeSabre VINs 400044-463322
Although the subject vehicles have been certified as complying with the applicable U.S. Environmental Protection Agency (EPA) and California Air Resources Board (CARB) On-Board Diagnostic (OBD) requirements, we have identified an OBD system improvement that should be implemented whenever practical.
Condition
The post catalytic converter oxygen sensor diagnostics for diagnostic trouble codes (DTC) P0137, P0138, P0140, and P0141 have been inadvertently disabled.
Affected Diagnostic Trouble Codes:
^ DTC P0137 H02S Circuit Low Voltage Sensor 2
^ DTC P0138 H02S Circuit High Voltage Sensor 2
^ DTC P0140 H02S Circuit Insufficient Activity
^ DTC P0141 H02S Heater Circuit Sensor 2
Cause
During the 1997 model year a production running change for Powertrain Control Module (PCM) calibration was released with the post catalytic converter oxygen sensor diagnostics inadvertently disabled.
Correction
Use a scan tool to verify what calibration is programmed into the vehicle's PCM. If the improved calibration has not been installed, re-flash the PCM with the updated calibration listed in this bulletin.
Calibration Information
The calibrations listed are FLASH calibrations and are NOT available from GMSPO. The calibrations are programmed into the vehicle's PCM via a techline tool device and are available from General Motors Service Technology Group (STG) starting with 1998 Disc 10.
Important:
Inform customers that this work is being performed on their vehicles to improve On-Board Diagnostic system operation and does not affect vehicle durability, reliability, or performance.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
J6355 Prom - Use published
Reprogramming labor operation
On Car time
Important:
This labor operation is covered under either the Federal or California Emission Control System Warranty (whichever applies) or the "Bumper-to-Bumper" coverage in the New Vehicle Limited Warranty. The warranty with the broadest coverage applies.