Oil Pressure Sending Unit (Everything To Know)

Are you very concerned about your oil gauge not working correctly? Is your oil pressure warning light on? If so, your vehicle’s oil sending unit might be faulty.

After reading this article, you will be well informed with all you need to know about an oil pressure sending unit, symptoms of a bad oil pressure sending unit, how to go about replacing it, and lots more.

In order for an internal combustion engine to run properly, several measures need to be taken. Oil is one of the primary things that make your car function effectively.

However, car engine oil would not be able to flow into the engine compartment without pressure. Oil pressure ensures that the lubricant circulates throughout the engine.

The engine oil would be useless without pressure, making it more like a dead engine. The best way to ensure pressurized oil in your vehicle is by checking the oil pressure warning light or oil pressure gauge.

The light or gauge can only function correctly if the oil pressure sending unit is working correctly.

The oil pressure sending unit is not complicated in design; it has two significant switches: the diaphragm and the spring-loaded switch.

The diaphragm is designed to always stay open at a specific pressure range after receiving the required oil.

This pressure moves the diaphragm to the spring-loaded switch, ensuring the warning light is off.

In other words, if the set pressure is not enough, the diaphragm will have nothing moving it to the spring-loaded switch, hence keeping your oil pressure warning light on.

Mechanical-related problems can cause low oil pressure in a car, such as low oil level, a bad oil pump, a clogged oil filter, and others.

All of these problems can pose a significant threat to your engine if not addressed quickly and correctly. The purpose of the oil pressure sending unit is to warn you and give you time to turn off your car before the engine is damaged.

Also Read: Oil Filter Housing (Everything To Know)

Types of Oil Pressure Sending Units

Types of Oil Pressure Sending Units

The three types of oil pressure unit are:

1. The first type of oil sending unit is the one that is being fed by a connecting tube; they are found at the output end of the oil pump. They are connected to the dashboard for reading.

2. The second type of oil pressure sending unit is attached to a unique dedicated oil location. It sends a signal through a wire while using a transducer attached to an electromechanical switch.

As your car keeps running, the oil pressure will drop over time. If it drops below a certain limit, a sign will appear on the dashboard.

This type will likely stay idle since oil pressure is determined by the engine’s revolutions per minute (RPM).

3. The third type of oil pressure sending unit uses the principle of electrical voltage output directly proportional to actual oil pressure.

Oil pressure switches are divided into three types, 1-pin, 2-pins, and 3-pins. The significant difference between these three types of pins is based on the wiring.

All oil pressure sending units serve the same purpose; sending signals related to oil complications in the engine, regardless of the type.

Is Oil Pressure Sending Unit the Same as Oil Pressure Switch?

The term oil pressure sending unit is no longer as widely used as it once was; the common name used by most professionals is either oil pressure switch or oil pressure sensors.

No matter the term used, all three provide the same service to the vehicle, monitoring oil pressure. In most cases, oil pressure sending units are attached to a gauge to display real-time reading of oil pressure on your dashboard.

The oil pressure warning light is sometimes controlled by the oil pressure switch or oil pressure sensor; it can also give out an oil pressure readout, depending on what the car manufacturer has decided to call the part.

What Happens When Oil Pressure Switch Goes Bad?

The oil pressure sending unit in your car can malfunction. When this happens, you will not know the actual state of your oil pressure.

If you leave your car oil pressure sending unit not attended to when it gets faulty, you will be exposing your car engine to a severe risk of several component damages.

Whenever you discover that your oil sending unit is malfunctioning, you should get it repaired as soon as possible. Like other car components, the oil pressure sending unit depreciates over time.

It is even more unpredictable since wear-related faults may develop at any time without any warning. Nevertheless, a faulty oil pressure sending unit will not automatically shut down your car and leave you stranded.

Your car gives similar warnings when it has problems with related components. You should fix your vehicle as soon as this sign appears to avoid further damage.

When in doubt whether your car has a faulty oil pressure switch or not, you can install an external gauge in its place to get an idea of what the oil pressure condition is. Below are the signs and symptoms of bad oil pressure.

Symptoms Of a Bad Oil Pressure Sending Unit

Symptoms Of a Bad Oil Pressure Sending Unit

Your vehicle’s oil pressure sending unit is an essential component of your car that should not be ignored, especially when malfunctioning.

This part is constructed to make it easy to diagnose a problem if it fails. Symptoms of low oil pressure sending unit include. One of the most easily seen signs of insufficient oil pressure is the automatic display of the oil pressure warning light.

If the oil pressure sending unit becomes faulty, it activates the warning light, and the light will remain on until it is fixed. There may be times when you need to check the oil level to figure out if everything is OK.

When that happens, it can be a warning that there is something wrong with the oil pressure sending unit, and it needs to be repaired immediately.

1. Oil Pressure Warning Light Blinks Inconsistently

An inconsistent blinking of the oil pressure warning light on the car’s dashboard is another possible sign of a faulty oil pressure sending unit.

Sometimes the oil pressure warning light will stay on, or it intermittently turns on and off other times.

Oil pressure warning lights that keep flashing are signs that the oil sending unit is malfunctioning and needs to be repaired immediately to prevent engine damage.

2. Inaccurate Oil Pressure Gauge Readings

You can tell the oil pressure sending unit is damaged or faulty if your vehicle’s oil pressure gauge reads the same reading every day for several days.

This might also be called a switch symptom. If you notice any of these symptoms, look into your oil pressure sending unit to verify the problem for proper fixing.

Check the oil level and contact an expert to examine it further and fix the problem. Do not procrastinate.

Make sure you check your car model and make before making a purchase.

How to Test an Oil Sending Unit

Whenever you notice your oil sending unit is showing signs of failing, it is a good idea to check it out, examine it, and test the components to determine whether something is wrong.

Here is a practical step-by-step way to examine and test your oil switch or oil sending unit.

Step 1:

Insert and turn car key to accessory setting To test the oil pressure sending unit in your car, you will have to get your car key and plug it into its place and switch it to the accessory setting so that you can continue testing.

Step 2:

Check the dashboard oil pressure gauge Observe that the key has been set to the accessory setting; check the oil pressure gauge on the dashboard.

If the dashboard gauge is reading zero, detach the wire on the oil pressure sending unit. If the reading reaches three, the oil pressure sending unit is damaged and needs to be repaired or replaced.

Step 3:

Check the disconnected wire against a metal part When you pick the loose wire, touch it with the battery negative terminal of the vehicle or any metal part of the vehicle, then check again on the dashboard if the gauge is reading zero.

If the indicator is zero, the oil pressure sending unit is fine.

Also Read: Car Leaking Oil When Parked? (Causes and Fixes)

How To Replace Oil Pressure Sending Unit

If you test and discover that the oil pressure sending unit is bad, you should replace it. It should only take a few dollars and a small amount of time.

To successfully change the oil sending unit, follow the procedure below.

  1. Make sure that the engine isn’t hot. If you are driving, pull over and give the engine time to cool down.
  2. Move to the hood, open it and get it hooked.
  3. Go to the battery and remove the cable from the terminals.
  4. Depending on the type of vehicle, detach the electrical oil pressure sending unit or the mechanical oil pressure sending unit.
  5. Get a wrench, place and tighten it on the sending unit and lose it.
  6. The oil pressure sending unit should be taped around to avoid leakage
  7. Use your hand to place the first thread of the new oil sending unit into its position, and when it has been properly fitted in, tighten it with the wrench.
  8. Reconnect the wring of the oil pressure unit.
  9. After you finish this process, insert the car key and start the car, then pay attention to the dashboard and observe the behavior of the warning light and oil pressure gauge.

If they are working correctly, you are good to go! If they are not, you may have to repeat the process more carefully.

Check out this video for more tips on how to replace an oil pressure sending unit

Frequently Asked Questions – Oil Pressure Sending Unit

What Happens When an Oil Sending Unit Goes Bad?

A faulty oil pressure switch may cause the oil pressure warning light on the dashboard to be constantly on or fluctuating between being on and off, or it will stop working, depending on how the device failed. A failed oil pressure sending unit may also cause the oil gauge on the dashboard to be pegged at high or entirely stop working at all.

How Much Does It Cost to Replace an Oil Sending Unit?

Oil pressure sending unit replacement costs between $20 – $100 for most vehicles.

Can an Oil Sending Unit Leak?

There is a tendency for Oil sending units to leak as they age. You will most likely see an illuminated oil pressure warning light when this happens. To be sure of this, you perform a clear check of the oil sending unit, and if you notice fresh oil that’s not leaking from another component, it’s might be from this part.

How Long Does It Take To Replace an Oil Sending Unit?

It won’t take the entire day to fix or replace an oil pressure sending unit. This can be done within 45 minutes to a couple of hours, depending on how severe the damage is and the technicality of your vehicle.

Is It Ok to Drive With a Bad Oil Sending Unit?

It is not advisable to drive your car while the Oil sending unit is malfunctioning. This will often result in your car engine light illuminating, even if nothing is wrong with your vehicle. Even worse, it might cause damage to some internal engine components without triggering any warning.

Why Does the Oil Light Come On and Off?

When there’s low oil pressure, it means the oil pump is not distributing enough oil, or there is not enough oil in the system for the pump to circulate. The oil is vital to keep the component of the engine lubricated, so whenever the oil light comes on and the pressure is low, please pull over and off the car engine.

Can I Be Able to Change My Car Oil Sending Unit Myself?

To change an oil pressure unit, lift up the hood, and Detach the electrical linkage out from the oil pressure sending unit. A wrench or deep-wall socket will be needed for losing the sending unit. To avoid leakage, wrap the oil sending unit with Teflon tape, wrap particularly around the thread.

How Can I Detect That My Oil Sending Unit Has Become Faulty or Bad?

Check the oil gauge on the dashboard. Disconnect the wires that go to the connected unit. If the indicator is at zero or goes up to three, it is a sign of a bad oil pressure sending unit and needs to be replaced as soon as possible.

What Does an Oil Sending Unit Do?

An oil sending unit is a vehicle’s component that activates the oil pressure warning light on your dashboard when the car does not have the required pressure for the engine to function. Its primary function is to give you enough time to put off your car’s engine before it is severely damaged.


In a vehicle, an oil pressure sending unit is responsible for activating the oil pressure warning light on the dashboard when oil pressure is insufficient for the engine to function.

However, having a bad or faulty oil pressure sending unit won’t shut down your car immediately, especially when the signs are not immediately apparent.

Nevertheless, leaving it unattended will cause a lot of damage to your car’s engine and, at some point, will result in a complete shutdown of your vehicle.

Scott Greene is a seasoned automotive technician for over 5 years and has been deep into advanced automotive diagnostics for a couple of years. He Loves writing about Automotive Diagnostics and Repair, Trouble codes, Buyer guides for various car parts and accessories, and lots more. 

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