What Causes the Oil Warning Light to Come On?

Written by byron walsh
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What Causes the Oil Warning Light to Come On?
When your oil light comes on, pull over and turn the engine off immediately to avoid damage. (Jupiterimages/Comstock/Getty Images)

Your car's oil warning light tells you when your oil pressure is dangerously low. Often mistaken for an indication of the oil level, the light actually activates when there isn't enough pressure to inject oil into the cylinders in the egine. Without the lubrication the oil provides, the cylinders can be damaged, leading to the need for a new engine. The oil warning light can come on as a result of several common problems.

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Low Oil Pressure

Low oil pressure is the most common reason the oil light in your car will come on. A sensor in your engine determines whether oil is being pumped hard enough to channel through narrow holes in the pistons and other engine parts. Without enough pressure, the oil will not reach necessary areas of the engine. The friction of the engine parts rubbing against one another will lead to heat and abrasion, quickly damaging the engine beyond repair.

Oil Pump Problems

In some cases, the low pressure may be caused by a faulty oil pump. The oil pump itself lifts oil out of the oil pan at the bottom of the engine and injects it into the engine from the top. If your oil pump is not functioning correctly, the pressure of the oil will decrease, activating the oil warning light.

What Causes the Oil Warning Light to Come On?
Oil pump problems can activate the oil warning light. (Jupiterimages/Photos.com/Getty Images)

Faulty Oil Pressure Sensor

The oil pressure sensor itself may sometimes become clogged with sludge from the engine, especially if the engine has not been properly maintained. A clogged oil sensor can give a false reading of low oil pressure, which will illuminate your oil light. Never assume, however, that an oil light coming on is because of a clogged sensor.

Low Engine Oil

Low engine oil is actually a rare cause of an oil light coming on. This is because the intake for the oil pump is located fairly low in the oil pan. A small amount of oil in the engine, even well below factory specifications, will circulate through the engine at a pressure high enough to avoid activating the sensor. The most common situations in which low engine oil causes the oil warning light to illuminate are unknown slow leaks in the oil system, an improperly replaced drain plug or oil filter and impacts to the oil pan from rocks or other road debris.

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