The oil pressure sending unit (also referred to as an oil pressure switch or oil pressure sensor) is a critical component in the vehicles engine system. The device is critical in ensuring the vehicle’s engine operates within safe oil pressure ranges.
This article provides an overview of the purpose, function and operation of the oil pressure sending unit, symptoms of a faulty unit, diagnostic strategies, and replacement costs.
What is Oil Pressure Sending Unit?
The oil pressure sending unit, also known as the oil pressure sensor, is a crucial component of your vehicle’s engine. Its primary function is to monitor the oil pressure within the engine and relay this information to the vehicle’s computer or dashboard gauge.
This ensures that the driver is always aware of the oil pressure status, helping to prevent engine damage due to low oil pressure. By keeping track of the oil pressure, the sending unit helps maintain optimal engine performance and longevity.
The oil pressure sending unit is typically located near the oil filter or on the engine block. It consists of a pressure-sensitive diaphragm or sensor that reacts to changes in oil pressure. When the engine is running, oil is pumped through the engine, creating pressure.
The sending unit measures this pressure and sends a corresponding signal to the oil pressure gauge on the dashboard or the engine control unit (ECU). This information allows the driver to monitor the engine’s oil pressure in real-time, which is critical for maintaining engine health.
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;
1. Fluctuating or Erratic Oil Pressure Gauge: A primary function of most oil pressure sending units is to provide a real-time signal representative of the engine’s oil pressure to the vehicle’s oil pressure gauge.
When the sending unit malfunctions, it can send inconsistent or incorrect signals to the gauge. This may cause the gauge needle to fluctuate rapidly between high and low pressure, even though the actual oil pressure remains constant.
2. Constant Low Oil Pressure Reading: A faulty oil pressure sending unit can cause the oil pressure gauge to incorrectly display a constant low-pressure reading when actual engine oil pressure is within acceptable limits.
3. Illuminated Malfunction Indicator Lamp (MIL): When the oil pressure sending unit fails, the vehicle’s onboard diagnostics system can illuminate the Malfunction Indicator Lamp (MIL). The MIL provides a visible indication that a fault may be present in the engine or in a monitored component.
While the oil pressure sending unit may not directly cause engine damage, it is important to have the vehicle inspected by a professional technician to determine the underlying cause and prevent potential problems.
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 Replacement Oil Pressure Sending Unit
Most types of oil pressure sending units light up when the oil pressure has reached nine pounds or less.
However, there are times when the unit malfunctions so that even if the pressure has reached below the critical level, the warning lights do not light up, such as when the issues mentioned above are present.
When this happens, you need to replace the oil pressure sending unit immediately to avoid serious problems with your car. Remember that when your car runs out of oil pressure, its engine can sustain serious damage.
Step 1 – Locate the Oil Pressure Sending Unit
Before you start working on the oil pressure sending unit in your car, make sure your vehicle is in a safe and secure position. To do this, pop the hood of the car, then prop the front of the vehicle using car jack stands.
After putting your car in a secure position, locate the oil pressure sending unit. You should be able to find the unit very close to the oil filter.
The pressure unit on newer car models usually has a round black ½-inch long cylinder, with two wire connectors. Older car models usually have small round units that are 1½ inches wide.
Step 2 – Check the Oil Pressure Sending Unit
To make sure that the problem is in the oil pressure sending unit, check the electrical connection of your car and make sure that the oil pressure sending unit is properly connected.
If the electrical connections of your car are good, but the oil pressure sending unit still fails, then it is time to change the unit.
Step 3 – Remove the Old Oil Pressure Sending Unit
To remove the old oil pressure sending unit, squeeze the connector, then pull it off using your gloved hand. After removing the connector, unscrew the unit and then lift it out.
Install the new unit inside the place where you remove the old one. Wrap Teflon tape around the threads of the new unit and then thread it into place.
Make sure that it’s not too tight, or the threads may break.
Step 4 – Reinstall the Electrical Connector
After installing the new unit, attach the electrical connector to the unit. Turn on the power of your car and see if the oil gauge works. If the oil gauge does not work, check the electrical connection and make sure that it is installed properly.
Once you’re sure that the new oil pressure sending unit is properly connected to your car, close the hood of the vehicle and remove the car jacks.
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.