* Low oil level: This is the simplest and most common cause. Check your oil level immediately using the dipstick. Low oil means the pump can't generate enough pressure when the engine is idling because there's simply not enough oil to pump.
* Worn oil pump: The oil pump might be failing. As it ages, its ability to pump oil effectively decreases, and the problem is more noticeable at idle when the pump is working under lower pressure demands.
* Worn bearings: Worn crankshaft or camshaft bearings increase the friction in the engine. This higher friction requires more oil pressure to maintain lubrication, which may drop below the sensor's threshold at idle.
* Clogged oil pickup tube or filter: If the oil pickup tube (which draws oil from the sump) or the oil filter is clogged, the oil pump struggles to get enough oil. This is more likely to cause issues at low engine speeds (idle).
* Thick or incorrect oil: Using oil that's too thick (too high a viscosity) for the operating temperature can also lead to low oil pressure at idle. Using the incorrect oil weight can also exacerbate this.
* Oil pressure sending unit/sensor failure (less likely): While less probable given the situation (it usually gives a constant or intermittent warning rather than one dependent on engine speed), a faulty oil pressure sending unit could be sending incorrect signals. This is less likely because the problem is speed-dependent.
What to do:
1. Check your oil level immediately. This is the first and most important step. Add oil if necessary, but don't overfill.
2. Check your oil pressure: If possible, get the oil pressure checked with a gauge by a mechanic. This provides a definitive reading, separating a genuine low-pressure issue from a sensor problem.
3. Change your oil and filter: Even if the oil level seems okay, a fresh oil change with the correct weight oil is a good preventative measure. A clogged filter can significantly impact pressure.
Ignoring a low oil pressure warning can lead to catastrophic engine damage. Have a mechanic diagnose and repair the problem promptly. Don't continue driving the vehicle extensively with this warning light illuminated.
