What is Oil Pressure Sending Unit? Symptoms, Causes and Fixes

Vehicles are designed with several computerized systems that make their operations completely easy for the driver. These systems communicate within the components of the car to inform the driver whether the parts are working correctly or not.

One of these essential computerized components is the oil pressure sending unit. Have you wondered why a vehicle would run short of oil without the driver having a slight notice of the problem? It is a problem that stems from a bad oil sending unit.

If this component is so important; then, what is an oil pressure sending unit in a vehicle, and how does it function? Let’s find out in the following section.

What is Oil Pressure Sending Unit?

Oil Pressure Sending Unit

A vehicle’s oil pressure sending unit is a mechanical device that regulates the oil flow within the engine compartment. The component is responsible for sending information about the vehicle’s oil pressure to the computerized system that helps to control the related indicators.

The oil pressure gauge and warning light indicators both rely on the information received from a vehicle’s computerized system to function effectively.

Meanwhile, the automated system further depends on the oil pressure sending unit to receive the signals that enable it to communicate with the gauge and the dashboard warning light.

Therefore, a malfunction in the oil sending unit means that a wrong signal or no signal would be sent to the computerized system, which further delivers information to the gauge and dashboard oil pressure warning light according to what it had received.

Now, have you been confused by someone trying to address a vehicle’s oil sending unit using the terms “oil pressure switch” or “oil pressure sensor”? Well, let’s find out whether they are different or similar.

Oil Pressure Switch

An oil pressure switch is a device fitted in the engine compartment of a vehicle to monitor oil pressure levels and turn on/turn off the corresponding oil pressure dashboard warning light.

The oil pressure switch is located on the vehicle’s engine block. The oil pressure warning light and other dashboard lights usually turn on when you start a car; then, turn off after a moment to indicate that they are functioning correctly.

Meanwhile, when a vehicle’s computerized system receives a wrong signal from the oil pressure switch, it will communicate the false information to the gauge and warning light. When this happens, the warning light may turn on and remain so for a long time until the fault is rectified or the switch is replaced.

Oil Pressure Sensor

If you are wondering, “How does an oil pressure sensor work?” The oil pressure sensor of a vehicle is a mechanical device that measures the pressure of the oil in the engine. Then, it sends a signal to the computerized system of the car, which further transfers the information to the vehicle’s oil pressure gauge and warning light, respectively.

An oil pressure sensor is technically used to address both the oil pressure sender and oil pressure switch. So, you may want to say that they are similar in functions. However, there is a slight difference between the two. Now, pay rapt attention to the next section below.

Oil Pressure Switch Vs. Sensor Differences

When contemplating oil pressure sending unit Vs. oil pressure sensor, both components may appear similar in function and, as such, they may be used interchangeably. However, the slight distinction between the two is:

  • The oil pressure switch simply activates or triggers the oil pressure warning light display when low oil pressure is detected. While;
  • An oil pressure sensor is responsible for measuring the actual pressure of the oil and sending the corresponding signal to the oil pressure gauge for appropriate reading.

What are the Symptoms of a Bad Oil Pressure Sending Unit?

A vehicle’s oil pressure sending unit is part of the essential components that shouldn’t be overlooked when it malfunctions. The part is designed in a manner that is easy to detect when it fails or goes bad. Some of the bad oil pressure sending unit symptoms includes;

how does oil pressure sending unit work

Oil pressure warning light display

One of the early symptoms of a bad oil pressure sending unit is the automatic display of the oil pressure warning light. The moment the oil sending unit fails, it triggers the warning light and sustains the display until the problem is rectified.

In some cases, you may check the oil level to find out that everything is just okay. In that case, it could be a quick notification that the oil sending unit is gradually going bad and needs immediate attention.

Inconsistent (blinking) display of oil pressure warning light

Another symptom that is closely related to the first one above is the inconsistent display of blinking of the oil pressure dashboard warning light. While the light stays on in the first instance, it turns on and goes off immediately in this case.

When the oil pressure light comes on and off constantly, it is a sign that a problem is imminent within the oil pressure sending unit and needs to be checked as soon as possible to avoid further damages.

Inaccurate oil pressure gauge readings

Have you found a vehicle’s oil pressure gauge reading zero from morning till evening, and even onto the next day? That’s it; there is a problem with the vehicle’s oil pressure sending unit. Sometimes, the gauge may read less or more than the actual oil pressure of the car.

The signs above are also almost the same as oil pressure switch symptoms. If you ever experience any of the three symptoms above, it is not time to ignore and manage your car driving around.

It is not even the right time to procrastinate after noticing these symptoms; it would be best to immediately check the oil level and contact an expert auto mechanic if you can’t rectify it yourself.

How Do You Test An Oil Pressure Sending Unit?

If you discover that your vehicle’s oil pressure sending unit is failing, it is the right time to test the component to figure out whether it is something to worry about or not. Here is a straightforward step-by-step guide on how to test an oil pressure sensor or sending unit.

Step 1: Insert and turn car key to accessory setting

Firstly, get your car key and insert it into its place and turn it to the accessory setting to enable you to commence the oil pressure sending unit test.

Step 2: Check the dashboard oil pressure gauge

Once the key is turned to accessory setting, take a look at the vehicle’s dashboard oil pressure gauge. If the dashboard oil pressure gauge reads zero, disconnect the wire on the oil sending unit. If it reads up to 3, it is a sign that the oil sending unit is bad and requires a replacement.

Step 3: Check the disconnected wire against a metal part

You can further pick the wire disconnected from the oil sending unit and touch it on the vehicle’s battery negative terminal or any metal part of the vehicle. Then, check again; if the oil pressure gauge reads zero (0), it means the oil sending unit is okay.

How To Replace Bad Oil Pressure Sending Units

Once you discover that your vehicle’s oil pressure sending unit is bad, probably after testing the component, it is recommended that you change it immediately. This will take a few dollars and a fraction of your time during the day. To replace the part, engage the steps below.

  • Park your vehicle and allow the engine to cool down.
  • Open the hood and raise it up. Then, get it hooked in place.
  • Disconnect the vehicle’s battery cables from their terminals to prevent being shocked.
  • Disconnect the wire connecting the mechanical oil pressure sending unit or the electric oil pressure sending unit, as the case may be.
  • Get an oil pressure sending unit socket or wrench. Fix it on the sending unit and loosen it.
  • Get some tape around the new oil pressure sending unit (to prevent any leaks).
  • Thread the new oil sending unit right into its position with your hand and tighten it with the socket or wrench. Then, reconnect the oil pressure sending unit wiring.

Finally, once the process is completed, insert the car key and start the vehicle. Then, check the dashboard oil pressure gauge and warning light to observe their operations. Once they function correctly, you are good to go! If they don’t; you may have to go through the process more carefully again.

How an Oil Sender works YouTube

FAQs

Q: Can I drive with a bad oil pressure sending unit?

Yes, driving with a bad oil pressure sensor or sending unit is possible. This is because the oil pressure sending unit’s function is to communicate the oil pressure of your vehicle to the computer system at all times. It doesn’t really impact the smooth running of your car.

However, driving with a bad oil pressure sending unit is not ideal because as simple as its function in a vehicle, neglecting it can be detrimental in the long run. How would you detect an oil pressure that’s lower than the ideal level when your car’s oil pressure sending unit is bad?

So, you will be risking imminent damage if you choose to drive with a defective oil pressure sending unit. It won’t cost a fortune to replace the part, so why waste time and risk greater damage to your car?

Q: What happens when an oil sending unit fails?

When a vehicle’s oil sending unit fails, it will automatically project inaccurate readings on the gauge. This will misinform the driver and prevent the ability to determine if there is a problem with the oil supply.

A failing oil sending unit will later trigger the display of the oil pressure warning light after displaying incorrect information on the gauge for a while. The remedy for this challenge is to replace the oil sending unit as soon as these signs are detected. It will only cost a few bucks.

Q: How much does it cost to replace an oil sending unit?

An oil pressure sending unit replacement cost wouldn’t require saving up a lot of money for a whole year. The part costs around $48 to $67, and the labor cost is around $73 to $93.

Why wait another day when you can simply replace your vehicle’s oil sending unit with a few dollars of an equivalent of $121 to $160? However, the cost of replacement varies from one region to another.

The parts dealer’s price and the auto mechanic’s fee are other factors that can also affect the amount you would have to spend on your vehicle’s bad oil sending unit. In any case, it is worth it; so, it would be best to stop contemplating and get it fixed as soon as possible.

Q: Are the oil pressure switch and sensor the same?

When considering oil pressure switch vs. sensor, kindly note that the oil pressure switch and sensor are not exactly similar in their functions.

A vehicle’s oil pressure switch is a protective mechanical device designed to monitor the pressure of the oil in a car. It triggers the oil pressure warning light display when low oil pressure is detected.

While monitoring the oil pressure, it helps to turn on or turn off the warning light when necessary. So, it basically controls the warning light indicator system of the oil pressure.

Meanwhile, the oil pressure sensor measures a vehicle’s oil pressure. Then, it sends a signal to the gauge on the dashboard to guard the driver against an imminent problem within the engine compartment.

Q: How long does it take to replace the oil pressure Sending Unit?

It doesn’t take the whole day to replace a vehicle’s oil pressure sending unit. The job can be done between 45 minutes to a couple of hours.

The time frame is dependent on the person doing the job. Someone who has been a DIYer for a long time wouldn’t spend so much time as one who’s just getting to do the minor repairs on their vehicle for the first time.

Also, the process can be pretty fast for professional auto mechanics because it is what they do almost every day.

So, if you decide to contact an expert auto mechanic to do the job, you should be ready to cruise your car within a short time compared to doing it yourself. However, go with the option that suits your preference.

Q: Do I need to drain oil to change the oil pressure switch?

You don’t need to drain the motor oil from its place when changing a vehicle’s oil pressure switch. So, this shouldn’t be something to worry about at all. A vehicle’s oil pressure switch can be replaced in a few steps as follows.

  • Stop the vehicle’s engine and allow it to cool.
  • Open the vehicle’s hood and disconnect the battery cables from the terminals.
  • Identify the oil pressure switch right there on the vehicle’s engine block.
  • Disconnect the wire on the oil pressure switch.
  • Remove the oil pressure switch using its removal socket.
  • Get sealant applied on the new oil pressure switch to be installed.
  • Thread the switch right into the engine block with your hand and tighten it with the same socket.
  • Then, reconnect the wire to the switch and start the vehicle to check it out.

Final Words

No doubt, it is common to use the terminologies “oil pressure sending unit,” “oil pressure switch,” and “oil pressure sensor” interchangeably. However, the slight difference that exists in their functions has been unveiled in this article.

Meanwhile, if you have a bad oil sending unit, it may not stop your vehicle’s engine from running, but it will undoubtedly leave some symptoms. It would be best to pay attention to those symptoms and do the needful to avoid further damages.

Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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