For 1990-2009 cars

# FALSE HIGH OIL PRESSURE GAUGE READINGS

1988 VEHICLES EQUIPPED WITH 3.8L MODELS/YEARS LG3 (VIN CODE 3), 3800 LN3 (VIN CODE C), AND 3.0L LN7 (VIN CODE L) V-6 ENGINES

Some of the above listed vehicles may exhibit false high oil pressure gage readings during normal engine operation.

This condition may be due to a loss of ground to the oil pressure switch mounted in the oil filter adapter (refer to Figure 1). The condition may be confirmed and corrected by the following procedure:

1. Verify that oil pressure gage reading high.

#### NOTICE: Normal engine oil pressure should be approximately 20 psi at idle in drive, with the engine at operating temperature; and approximately 45 psi at 2000 E.R.P.M. in park with the engine at operating temperature.

2. Ground the bass of the oil pressure sensor to the negative battery terminal or a known good chassis ground.

3. If procedure stop 2 causes a correction in the pressure gage reading, remove and discard the four (4) bolts that attach the oil filter adapter to the front cover. Install a new oil filter adapter, gasket, part number 25529916 and replace the original bolts with four (4) bolts, part number 25534181. Torque the new bolts to 17 N - m (12.5 lbs. ft.).

4. Verify that the oil pressure gage is reading correctly and inspect the oil filter adapter gasket area for leaks.

If the above does not cause a change in the pressure gage reading, or if the new reading is below recommended minimum oil pressure, follow the normal service diagnostic procedure for the engine oiling system.

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.