For 1990-2009 cars

# Tech - On Board Diagnostic (OBD) System Improvements (Reprogram PCM)

Subject: | On-Board Diagnostic (OBD) System Improvements (Reprogram PCM)

Models: | 1998 Buick Century, LeSabre, Park Avenue, Regal, Skylark

| 1998 Chevrolet Camaro, Lumina, Malibu, Monte Carlo, Venture

| 1998 Oldsmobile Achieva, Cutlass, Eighty-Eight, Intrigue, Silhouette

| 1998 Pontiac Bonneville, Firebird, Grand Am, Grand Prix, Trans Sport

| 1998 Chevrolet and GMC C/K Pickup, G, M/L, P, S/T Trucks

| 1998 Oldsmobile Bravada

| with 3.1 L, 3.4 L, 3.8 L, 4.3 L, 5.0 L or 5.7 L Engine (VINs M, E, K, 1, W, X, M, R -- RPOs L82, LA1, L36, L67, L35, LF6, L30, L31)

Although the subject vehicles equipped with the listed engines 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 as necessary.

### Condition

1. When using a generic scan tool (non-Tech II), catalyst monitoring test results will not be available once the engine is shut off.
2. Erroneous idle catalyst monitor test values will be reported to the technician if using a generic scan tool (non-Tech II).

### Cause

1. Catalyst monitoring test results are stored in volatile RAM and are only available from the completion of the test until key-off.
2. Due to a software anomaly, erroneous idle catalyst monitor test values and limits will be reported which can confuse a service technician.

### Correction

1. Record catalyst monitoring test results prior to turning the engine off when using a generic scan tool (non-Tech II).
2. When using a generic scan tool, recalibrate the vehicle with the latest calibration available for the vehicle application, if test data are required for vehicle diagnosis. Recalibration will correct the software anomaly which reports the incorrect data.

### Calibration Information

The calibrations are programmed into the vehicle's PCM via a Techline tool. Calibrations are available from General Motors on the TIS 2000 Disc #17 CD ROM.

### Warranty Information

For vehicles repaired under warranty, use:

Labor Operation | Labor Description | Labor Time
--- | --- | ---
J6355 | Prom -- Reprogramming on vehicle | Use Published Labor Time