GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 42907 Oil Pressure Gauge Adapter.
    • J 21867 Pressure Gauge.
    • J-21867-16 Oil Pressure Adapter.

    Important: This test is performed to verify the operation of the cylinder deactivation oil pressure relief valve located in the oil pan. Refer to Lubrication Description and Cylinder Deactivation (Active Fuel Management) System Description.


    Object Number: 2043986  Size: SH
  1. Remove the oil filter and install the J 42907  (2).
  2. Install J 21867  (1), or equivalent, to the J 42907  (2).
  3. Remove the oil pressure sensor. Refer to Engine Oil Pressure Sensor and/or Switch Replacement.

  4. Object Number: 2043988  Size: SH
  5. Install the J-21867-16  (1) to the valve lifter oil manifold (2).

  6. Object Number: 2043990  Size: SH
  7. Install the J 21867  (1), or equivalent to the J-21867-16  (2).

  8. Object Number: 2043992  Size: SH
  9. Run the engine and measure the engine oil pressure while observing both gauges (1 and 2).
  10. Operate the throttle, as required, to increase and decrease the engine oil pressure.

    • With the engine running and the lower pressure gauge (2) measuring below 379 kPa (55 psi), both gauges should display the same pressure reading. If the readings are not the same and the lower gauge (2) has a higher reading, the cylinder deactivation (active fuel management) oil pressure relief valve is stuck in the open position or the valve lifter oil manifold filter is plugged.
    • With the engine running and the lower pressure gauge (2) measuring above 379 kPa (55 psi), the upper gauge (1) should display no greater than 379-517 kPa (55-75 psi). If the reading on the upper gauge (1) is greater than 517 kPa (75 psi), the cylinder deactivation (active fuel management) oil pressure relief valve is stuck in the closed position.
  11. Repair, as required.