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What Is an Oil Pressure Sensor?

Engine wiring with oil pressure sensor

Much has been said about the important role oil plays in an engine. Aside from being a cornerstone of regular maintenance, making sure you have enough oil and that it’s doing its job is something that needs monitoring every time you run the engine. An oil pressure sensor helps monitor the presence and pressure of oil in the engine and will alert you if something is wrong. Here’s how it works, and what happens when it doesn’t.

Failure to Lube

Oil is best known for coating moving engine parts, like pistons, to prevent damage from friction and heat. Aside from lubrication, oil also cools as it travels, taking potentially damaging heat with it, and picks up small debris and particulate matter created in the engine’s normal operation.

This is why filters are important — they collect and keep debris from recirculating — and why both filters and the oil itself must be periodically changed. Under normal conditions, you shouldn’t have to add extra oil between changes. If you do, your engine is likely burning it irregularly, or you have a leak somewhere. Too little oil, or under-pressurized oil, is not going to do its job and will quickly lead to larger problems.

Sensory UnderloadOil pressure sensor

The oil pressure sensor is mounted directly into an oil gallery. When the engine starts, an oil pump pressurizes the system, including oil in the gallery. The sensor can be designed in a few ways, but the basic idea is that when there’s pressure on the side of the gallery, a diaphragm in the sensor moves the position of electrical contacts inside to send a signal to the dashboard and the electronic control unit. This signal tells you and the computer whether the oil pressure is right for the engine.

That’s Oil, Folks

Immediately check the oil levels any time you get a warning light. A low pressure reading could be the result of several problems such as low oil, a bad pump, a restriction in flow or a bad sensor. Some problems are more serious than others, so it’s important to know exactly what the problem is as soon as you see a warning light.

There are a couple signs that you have a bad oil pressure sensor. Your sensor is probably not doing its job if the oil pressure light is blinking, if you see an oil pressure light come on when the actual oil pressure is fine or if you get a bad gauge reading.

A bad sensor isn’t too hard to change, or you could bring it to a trusted mechanic. Knowing your sensor is working properly gives you peace of mind that your car is being monitored as it should be.

Check out all the engine lubricating system parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on oil pressure sensors, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.


Blair Lampe View All

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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