* Low oil pressure: This is the most common cause. Even if the oil level is correct, the pump may not be generating enough pressure to adequately lubricate the engine. This could be due to:
* Worn oil pump: The pump itself might be failing.
* Clogged oil pick-up tube or screen: Debris can restrict oil flow to the pump.
* Thickened oil: Using the wrong viscosity oil (too thick for the temperature) or oil that's degraded can impede flow.
* Bearing wear: Worn crankshaft or camshaft bearings allow excessive oil leakage, reducing pressure.
* Leaking oil seals: Similar to bearing wear, seals can leak oil, lowering the pressure.
* Damaged oil cooler: A blockage or leak in the oil cooler can affect pressure.
* Faulty oil pressure sensor or sending unit: The sensor itself might be malfunctioning, giving a false reading of low pressure even if pressure is fine. This is less likely if the light stays on consistently.
* Low oil viscosity (too thin): While unlikely to cause a light at idle if the oil is *newly* changed, extremely thin oil might not build enough pressure at low RPMs.
It's crucial to not ignore an oil light. Continuing to drive with insufficient oil pressure can lead to catastrophic engine damage, potentially requiring a rebuild or replacement. Immediately stop driving and have the vehicle towed to a mechanic for diagnosis. Running the engine only briefly to get it to a safe place is acceptable.
The mechanic will need to diagnose the specific cause of the low pressure. They will likely check the oil pressure with a gauge, inspect the oil pump and its components, and potentially perform further diagnostics depending on the results.
