Oil Pressure Sensor: Low Oil Pressure Warning Light Comes On And Off

Engine Related Issues

By Rodney (Mechanics)

When the engine losing oil pressure, it will caused the indicator light of engine oil pressure warning is on. If engine losing oil pressure, it can causing the engine severely damaged, so stop driving and turn off the engine.

How The Low Oil Pressure Light Comes On And Off

There many factors that most likely caused the oil pressure gauge, low oil pressure warning light comes on and off, defective sending unit of oil pressure, warning light switch, or low oil level, or bad oil pump.

Diagnosis of Low Oil Pressure Light

Checking first the oil level to determine if it low or full by take look on the dipstick.

Low oil level and oil consumption in engine most likely caused by oil leaks. It occur at timing cover gaskets or oil pan, the rear and front the seals of crankshaft oil, or the valve cover. For signs of oil leakage, check the bottom, sides and top of the engine. The check can be started by looking for heavy accumulations of grease, oil dripping or greasy stains on the ground. More miles on engine, the big chances have a leaking problem with gaskets and seals. If gaskets and seals causing engine leaking oil, you need to replace the gaskets and seals.

Leaking Oil Pan Gasket
Leaking Oil Pan Gasket

If the oil level is low and no oil leak was found and the outside of the engine is clean, probably valve guides, valve guide seals, or worn piston rings that causing the engine burning the oil. high mileage wear or neglect could be the reason it occur. It will be expensive to fix due replacing or rebuilding the engine is the way to fix oil consumption problem.

Check the dipstick frequently and keep adding oil as needed, if the oil use isn’t too intense (per 1000mph under 1 quart of oil). However, keep plenty of oil on hand and check the dipstick continuously if the engine is utilizing plenty of oil (per 500 miles more than a quart). Soon or later the engine need to be overhauled or replaced if it worn out due the engine is burning a lot of oil.

Low Oil Pressure Notes

NOTE: In the engine’s oil pan, there’s an oil level sensor that can causing oil warning light turn on when the level of oil is low (occur on some engines only). The engine could burning the oil, leaking oil or both, if the dipstick indicates a low oil level (you don’t see an oil on dipstick or level of oil below or at ADD line).

NOTE: On some engines, if the original seals and guides are worn, the way to fix oil burning problem (reducing oil burning) you need to replace the valve guide seals.

Bad Oil Pump

Bad oil pump can causing engine running with noises, check the oil level between ADD and FULL. Until the problem can be repaired, DO NOT run the engine. The way to checking oil pressure can be done by attaching the pressure gauge into the engine where unit of the oil pressure sending is attached. If the oil pressure measure results reads per 10 psi per 1000 RPM (normal specifications), it mean the oil pump is good. However if the result is not within specifications (less than from normal), it tell the engine bearings might be worn or could be the oil pump is worn.

Oil Pressure At 1000 RPM

After the warning from oil pressure light came on, the level of oil is between “full” and “add”, and when the engine run normally there are no noises come out, you can suspect the problem could be oil the pressure gauge, warning light switch or a defective oil pressure sending unit. Try to start the engine and drive the vehicles, however STOP driving and shut off the engine if the engine starts to become noisy.

How to Fix Low Oil Pressure Problem

Here are some ways how to fix low oil pressure problem. There is an easy way and a medium level task that requires testing tools to determine the source of the problem.

Add Oil To The Engine

Bring the level up the oil to the FULL mark on the dipstick by adding oil to the engine if the oil level is low. Never overfill the crankcase. Refer to owners manual and only use the appropriate oil viscosity specified type.

Replace The Oil Pressure Sending Unit

Directly to the engine, connect a pressure gauge and remove the sending unit of oil pressure, if warning light of oil pressure still on or the oil pressure gauge reading remains low. Check the pump if it is generating adequate pressure by started the engine. It is not a bad oil pump problem if the output is per 1000 RPM about 10 PSI, the output tell you the pressure is normal, so you can suspect oil pressure sending unit if it’s fault.

Try replacing the oil pressure sending unit with a new one, if you can’t testing oil pressure due you don’t have the pressure gauge. The problem has been fixed, if the gauge reading output is now normal or the warning from oil pressure light is off. Suspect the bad oil pump if low gauge reading continues or the warning from oil pressure light still on.

Replace The Oil Pump

The oil pump need to be replaced if the oil pump does not produce adequate pressure due oil pump is bad. On the bottom of the engine, inside the oil pan where the oil pump is located on most engines. If you want to replace the oil pump, you need to remove the pan. Removing the pan require removing steering or removing suspension components or raising the engine. On some another engines, on the front of the engine, inside the timing cover there you can find the oil pump. To access the pump, most of the components on the front of the engine need to be removed. This kind of pump will consuming more time and more difficult to replace.

If worn engine bearings that causing oil pressure is low, then you need to replace the crankshaft bearings. And most case like this requires replacing or overhauling the engine.