Oil Pressure Diagnosis and Testing

WARNING: This page is about a different variant/trim than selected.

Tools Required

With the vehicle on a level surface, run the vehicle for a few minutes, allow adequate drain down time, 2-3 minutes, and measure for a low oil level.
If required, add the recommended grade engine oil and fill the crankcase until the oil level measures full on the oil level indicator.
Run the engine briefly, 10-15 seconds, and verify low or no oil pressure on the vehicle gauge or light.
Listen for a noisy valve train or a knocking noise.
Inspect for the following:
- Foamy oil
- Slow idle speed
- Plugged oil filter
- Oil diluted by the following:
  - Water
  - Engine coolant
  - Unburned fuel mixtures
- Malfunctioning oil filter bypass valve
- Incorrect or faulty oil pressure gauge
- Incorrect or faulty oil pressure gauge sensor
- Improper engine oil viscosity for the expected temperature

Fig 1: Oil Pressure Sensor Wiring Harness And Oil Pressure Sensor

Courtesy of GENERAL MOTORS COMPANY

Disconnect the oil pressure sensor wiring harness (1).
Remove the oil pressure sensor (2) from the oil filter adapter.
Install the J-21867 Pressure Gauge with the EN-21867-850 Active Fuel Management Oil Pressure Adapter.
Measure the engine oil pressure.
Compare the readings to the Engine Mechanical Specifications .
If the engine oil pressure is below specifications, inspect the engine for one or more of the following:
- Loose oil filter adapter bolts
- Missing or damaged oil filter adapter O-ring seal or seals
- Worn or dirty oil pump
- Loose oil pump-to-engine block bolts
- Loose, plugged or damaged oil pump screen
- Missing or damaged oil pump screen O-ring seal
- Damage or leak in the oil pump screen suction tube
- Malfunctioning oil pump pressure regulator valve
- Missing or incorrectly installed oil gallery plugs
- Loose camshaft intermediate drive shaft bolts
- Excessive bearing clearance for the following:
  - Connecting rod or rods
  - Crankshaft
  - Camshaft or camshafts
  - Camshaft intermediate drive shaft sprocket
- Cracked, porous or restricted oil galleries
- Broken valve lifters
Repair or replace components as necessary.