P1189 BUICK Possible Causes
- Faulty engine oil pressure switch
- Engine oil pressure switch harness is open or shorted
- Poor electrical connection in the engine oil pressure switch circuit
How to Fix Code P1189 BUICK?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
When is the Code Detected?
If the engine has not been started and oil pressure has been detected, code P1189 will set.
Possible Symptoms
- Engine light on (or engine warning light soon on)
P1189 BUICK Meaning
The low oil pressure sensor is normally closed. When oil pressure rises above 1 to 4.5 psi, the switch contacts open. The Powertrain Control Module (PCM) provides 12 volts to the oil pressure input circuit. With low oil pressure, the 12 volts is pulled to ground. This diagnostic tests for an open condition in the oil pressure switch circuit. If the engine has been shut off long enough for the engine temperature to drop by 10°C, a short circuit (low oil pressure) in the circuit should be observed before cranking the engine.