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Why is my oil pressure light staying on, after replacing the sensor?

posted 8 years ago by MandrasAndPelagia
2 replies | jump to latest

My oil was leaking pretty bad...it was literally falling out every time I refilled it. Both the "oil pressure" and low oil light came on while driving.

I drove it for a week like this, prepared to trade it in for a new car. I just had to refill it with 1/4 of a quart of oil before EVERY start. Everywhere I parked I made the parking lot a mess.

So finally I wanted to find the source of the leak - after doing some research online, I raised my car up, started it, and saw oil pouring out of the "oil pressure" sensor. I found the source of my leak!

I went to Auto Zone and bought a new oil sensor, screwed it in myself. The next day, to my surprise, when I started my car, my LOW OIL light didn't come on! And I checked my oil level, and it was more than full. It worked!

BUT - I spoke too soon. On the way home, my low oil came on again. So I added a bit of oil. The OIL PRESSURE light came on again. But oddly, I looked underneath the car, and there were no signs of oil leaking. As far as I know, my oil is staying in there now, yet both lights come on. Why? Is it just a computer glitch?

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[–] dksix 8 years ago

Depending on the age of the car it could be a few things. But the first test is to do a manual oil pressure test. This will tell you if the engine is maintaining proper pressure. If the engine is maintaining pressure you will need to look for alternate problems, such as an oil level sensor (some cars have one) or that the oil pressure gauge (if it has one) is reading correctly. The gauge failing may cause the computer to see a general fault and turn on the warning lights.

If the oil pressure test indicates poor or failing pressure you could be looking at a bad oil pump or worse, such as worn main bearings that are causing washout.

[–] shadylady21 8 years ago

If I may ask, what type of motor do you have? Make and size. I see this problem a lot. After removing sending unit/ pressure switch there may be a small filter screen that goes in before the switch. These become plugged often. I also agree with previous poster about checking with a pressure gauge. Probably can rent one from parts store. Remove switch and screw in gauge, start motor and check the number. At cold idle it should read around 40 psi. Does your dash have an oil pressure gauge or just a light? Do you have to fill the coolant every so often? An intake manifold or head gasket can send antifreeze into the crankcase. Antifreeze is like acid to engine bearings. Do you hear a clicking sound when engine is running? If oil pressure is really low the lifters that open and close the valves may be dry causing the clicking sound. If you hear a deeper clunking sound then the racer bearings on the main crank may be bad. I'll try to help as much as I can. Take care and good luck!