The oil pressure sending unit is one of the parts of a car that most drivers are not aware of and likely have never even heard of before. If it pops up in conversation with another driver or your mechanic, you may be wondering exactly what this part is and what it does in your vehicle. Obviously from the name it has something to do with oil pressure. In fact, the oil pressure sending unit regulates the flow of oil throughout your vehicle. Oil pressure information is sent from the oil pressure sending unit to your car's computer to help everything run smoothly by indicating whether or not you have a problem with your oil pressure.
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If you have low oil pressure, for instance, the pressure sensor receives that information and you'll get a warning light on your dashboard to let you know that you have low oil pressure. There are actually different kinds of oil pressure sending units in cars so you may have a different kind of oil pressure sending unit depending on the make, model, and year of the vehicle you have.
Older model vehicles may have an oil pressure sending unit that's located in the output side of their oil pump that links to the instrument panels to provide a reading through a connecting tube.
Some vehicles will have an oil pressure sending unit that is a transducer attached to a mechanical switch that just screws into place to monitor your oil pressure. It's connected by a wire to the lights on your instrument panel to let you know when you have a problem with your oil pressure.
A slightly more advanced version of this transducer type of sending unit uses electrical voltage output that is proportional to the oil pressure to alert you to whether or not you have an issue with your pressure. Regardless of what kind of oil pressure sending unit you have; they should all do the same job effectively to let you know by way of setting off a warning light if something is wrong.
What is the Difference Between an Oil Pressure Sending Unit, an Oil Pressure Switch, and An Oil Pressure Sensor?
You may have heard any of these three terms used to describe parts of your vehicle. Oil pressure sending unit is one of the least used terms actually and you'll likely hear oil pressure switch or oil pressure sensor more often. Confusingly, all three do basically the exact same job.
In the most technical terms, an oil pressure sending unit should move a gauge on your dashboard while an oil pressure switch should turn lights on. An oil pressure sensor may do both and some other things besides as the term sensor is kind of vague in terms of what it can do in a vehicle. But this is all semantics and terminology. If someone is referring to an oil pressure sending unit, an oil pressure switch or an oil pressure sensor, they're probably talking about the exact same thing.
Usually, but not always, an oil pressure sending unit refers to an older part on an older vehicle. Many modern cars don't use oil pressure gauges any longer to let us know how the oil is doing rather they use an electronic readout. But, if your dashboard does have a gauge which means there is a needle that goes up and down to indicate the pressure, it's possible you do have an oil pressure sending unit specifically.
What Are the Symptoms of a Bad Oil Sending Unit?
If the oil pressure sending unit in your car isn't working correctly then you're not going to be getting warnings that you have a problem with your oil pressure. If you have a severe enough issue you could end up causing serious damage to your car because you don't realize that something is wrong. That's why having these early warning lights to let you know something needs to be addressed is so important. And of course, an oil pressure sending unit is susceptible to wear and tear just like any other part of your car. If you're experiencing any of these symptoms, it's possible that you have an issue with your oil pressure sending unit and should definitely get it looked at to see if it's the root of the problem or not.
Oil Pressure Light On
The whole purpose of the oil pressure sending unit is to illuminate the oil pressure light when there is a problem. But if the light comes on and you check your oil and find that everything is perfectly fine, then it's possible you're getting faulty signals from the oil pressure sending unit. As it starts to go bad on you, regardless of what kind it is, it could have been sending the incorrect signals that are going to produce incorrect readings. You'll definitely know this was the case if you put in a new oil pressure sending unit and the problem goes away.
Oil Pressure Gauge at 0
If you have an actual oil pressure sending unit as opposed to an oil pressure switch or an oil pressure sensor, then there's a good chance you actually have an oil pressure gauge. Like we said, sending units usually work with gauges. When you have a problem with your oil pressure sending unit then the gauge may be reading zero even when you have perfectly normal oil levels. If that's the case, then you can be fairly confident that the sending unit is the problem. It's not a guarantee, but there's a high likelihood. Even modern cars that use gauges attached to oil pressure sensors can read zero if the oil pressure sensor is sending a faulty electronic signal.
Blinking Oil Pressure Light
For the most part your oil pressure light should either be off because everything is fine or be on because there's a problem. If the oil pressure light is blinking on and off intermittently then that's a clear indication that you have an issue and a likely culprit is the oil pressure sending unit. Obviously you don't want to be checking your oil every time the light comes on and then turns off again so checking the sending unit or sensor itself may resolve this problem so that the light only comes on when you actually have an issue related to the oil pressure.
Can I Drive with a Bad Oil Pressure Sending Unit?
It's possible you can drive with a bad oil pressure sending unit although it's not recommended that you do so. Arguably, if there's nothing wrong with your oil pressure at all and it's just the bad oil pressure sending unit giving faulty signals you could drive for quite a while with no issues at all. The problem is you won't know when a problem does crop up until it's too late.
Think of driving with a bad oil pressure sending unit kind of like driving with no seatbelt on. If you don't get into an accident then there's no problems, right? However, if something bad does happen you're definitely going to regret it. That's why making sure your oil pressure sending unit is working correctly is the right thing to do to save yourself a hassle further down the road. Remember, if there is a problem with your oil pressure and your engine isn't able to keep properly lubricated for instance it could end up overheating and causing some severe damage that may end up costing you thousands of dollars in repair bills.
How Do You Test an Oil Pressure Sending Unit?
It's possible you can test your oil pressure sending unit to find out if it's actually malfunctioning or not before you go out of your way to buy a new one and have it replaced. You can do this on your own without having to even go to a mechanic and spend the money there either. The first thing you need to do is locate where it is in your car. Typically, this is located near the back and top of the engine compartment bolted into the engine block. It should be connected by some kind of wire or clip to the car's computer as well. If you're not sure where yours is after you take a quick look, then you're going to want to Google your make and model of vehicle to find out for sure exactly where it is so you can test it.
Once you locate your oil pressure sending unit you need to unhook the wire that connects it and ground it. Your gauge should rise at that point as high as it's able to go. If that happens then your sending unit is still sending the correct signals.
Another option for testing your oil pressure sending unit is to simply swap it with one from a car that isn't having any issues. If your sending unit works fine in the other car and that sending unit is still giving the malfunctions in your car, then you may actually have a problem with your oil pressure and not the sending unit. However, if the sending unit produces the same malfunctions in the other car then you know the sending unit itself is sending faulty signals.
Finally, you can use a multimeter like you would use to test your battery to test your sending unit or sensor. The way this works depends on the kind of sending unit or switch that you have. You want to make sure that your oil pressure actually is fine before going through with checking the sensor itself or the sending unit.
You'll need to set the multimeter to measure resistance or a closed circuit if it's able to test for that. Once you've done that, you'll need to remove the cables that connect your switch to the generator control system. If you don't do that it's going to affect the signal reading that you get.
Regardless of the kind of sending unit that you have in your car, when you test it with a multimeter it should show you that you have a closed circuit when your engine is at rest. When the engine is running the circuit should be open. If these signals aren't what you are reading, then you have a problem with your sending unit and should get it replaced.
Oil Pressure Sending Unit Replacement Cost
If you're having a problem with your oil pressure sending unit and you need to get it replaced, the cost of getting a new one is not too over-the-top. Again, the make, model, and year of your vehicle is going to have the biggest effect on the price you have to pay for a new oil pressure sending unit. That said, you can expect to pay probably somewhere between $16 and $100 to get a new one. You can check them out on AutoZone and see which one fits your make and model of vehicle.
The Bottom Line
An oil pressure sending unit has a remarkably simple job. It just monitors your oil pressure and then alerts you when something is wrong with it. Essentially it just turns on a light and nothing more. As simple as that is, it's incredibly important because imagine what your car would be like if that light was not there to warn you of a problem. Issues with your oil pressure can get very bad very quickly. The longer you drive with low oil pressure or low oil itself the more damage you're likely to cause to the point that your entire vehicle can shut down and you're going to end up spending thousands of dollars to get things fixed. All of that can be prevented for the cost of a $16 sensor that you can pick up from an auto supply store.
For those reasons it's important to keep an eye on you or oil pressure sending unit and if you can tell that yours is glitching on you and sending incorrect signals, take the time and money to get yourself a new one before a real problem arises that you won't be aware of because you're sending unit isn't able to send you the correct signals.