Oil Pressure Sending Units: Everything You Need to Know

The oil pressure sending unit is a necessary safety element. It is essential to understand its function and how to correctly repair or replace it because a malfunctioning unit can cause incorrect oil pressure readings, warning lights, or engine damage.

This article will provide a detailed overview of oil pressure-sending units and tell you how to maintain or replace them as needed to avoid costly repairs.

Oil Pressure Sending Units Everything You Need To Know

Oil Pressure Sending Unit: How Does It Operate?

The oil pressure sending unit is a safety tool used to track changes in oil pressure in an automobile’s engine. It can be found in the engine block.

The oil pressure sending unit monitors the oil pressure as the engine runs, and if it drops below a safe operating pressure range, it sends an electronic signal to the engine control module (ECM) to instruct it to shut down the engine to avoid significant damage.

The diagram shows an oil pressure switch
The diagram shows an oil pressure switch

There are two types of oil pressure-sending units: switch-based and variable-resistance based.

1. Switch Based Oil Pressure Sending Unit

The switch-based oil pressure sending units works by converting the oil pressure level into an electrical signal. The oil pressure-sending unit consists of a spring-loaded switch and a movable diaphragm.

When the oil pressure reaches a certain level, the switch inside the oil pressure-sending unit closes, completing an electrical circuit. This sends a signal to the oil pressure gauge on the dashboard, which then displays the oil pressure level to the driver.

If the oil pressure drops below the specific range (3.5-11 psi), the switch inside the sending unit will open, breaking the electrical circuit. This will cause the oil pressure gauge to display a low oil pressure warning light, indicating that the engine may be experiencing problems.

2. Variable-Resistor Based Oil Pressure Sending Unit

A variable-resistor-based oil pressure-sending unit works by using a variable-resistance oil pressure sensor. In this method, a variable resistor sensor provides a continuous signal that varies according to the oil pressure level instead of using a switch to indicate the level of oil pressure.

The movable diaphragm moves when oil pressure is applied to it.This movement changes the position of the resistive element in the sensor, which in turn changes its resistance value.

The ECM receives an electrical signal when the resistance changes.The ECM  interprets this electrical signal and displays the oil pressure reading on the dashboard.

Watch the YouTube video below to learn more about how the oil pressure-sending unit works.

3. Location of Oil Pressure Sending Unit/Switch

The oil pressure sending unit is frequently found on the cylinder head, close to the oil filter, or on the engine block. It might also be found on the back of the engine in some vehicles.

It is recommended to consult your car’s repair manual to determine the precise position of the oil pressure sending unit in your vehicle.

A Faulty Oil Pressure Sending Unit: The Common Causes And Preventions

The oil pressure sending unit in your car could stop working for a number of reasons.The list below shows what causes the oil pressure sending unit to malfunction and how to fix that. 

A defective oil pressure sending unit can be caused by a number of common factors, such as:

  • Wear and tear– The diaphragm of the oil pressure sending unit may deteriorate or wear with time, providing inaccurate readings.
  • Clogged oil pressure sending unit– The unit may get clogged with dirt, rust, or other contaminants, leading to failure.
  • Electrical issues– The oil pressure-sending unit may break down due to faulty wiring, a broken electrical circuit, or a blown fuse. 

To prevent an oil pressure-sending unit from malfunctioning, you can do the following things:

  • Change the engine oil regularly– Regular oil changes can help avoid the accumulation of contaminants in the engine, extending its lifespan and improving its performance.
  • Maintain proper oil levels– Regular oil checks and maintenance are crucial since low oil levels mean oil is not reaching all engine parts. It might lead to engine failure due to a lack of lubrication.
  • Replace damaged components– If the oil pressure sending unit or related parts show any symptoms of wear and tear or other damage, you should have them inspected and replaced by a mechanic.
  • Regular vehicle maintenance- Updating and inspecting your car on a regular basis might help you spot and fix issues with the oil pressure-sending unit early on.

Indications of a Malfunctioning Oil Pressure Sending Unit

There are certain indications of a malfunctioning oil pressure sending unit you may follow up to take action accordingly. 

Indications Of A Broken Oil Pressure Sending Unit

  • Low oil pressure warning lights
  • Fluctuating oil pressure gauge
  • Loud noises from the engine
  • Oil leaks

Low oil pressure warning lights– One of the most common indicators of a malfunctioning oil pressure sending unit is the low oil pressure warning light on the dashboard. It indicates low oil pressure, which could significantly harm the engine if ignored.

This sign on the dashboard indicates low oil pressure.
This sign on the dashboard indicates low oil pressure.

Fluctuating oil pressure gauge-If the oil pressure gauge on the dashboard fluctuates or displays inaccurate values, this may be a sign of a damaged oil pressure sending unit. It happens when this unit gives the ECM erroneous values of the oil pressure.

Loud noises from the engine- Rattling or knocking noises in the engine can be a sign of low oil pressure. It’s crucial to treat the problem right away if you hear these noises because they could be a sign of significant engine damage.

Oil leaks- An oil pressure-sending unit that isn’t working properly can cause oil to leak from the engine.

It’s crucial to take care of the problem right away if you experience any of these symptoms to prevent further harm to the engine or other parts of the vehicle. 

How To Replace An Oil Pressure Sending Unit: Detailed Instructions

It might be a very simple process to replace an oil pressure-sending unit. To protect other engine parts, it’s essential to take the necessary safety precautions. The table below shows the overall safety precautions in brief.

Safety Precautions

  • To prevent burns, always turn off the engine and work on a cool engine.
  • Before starting work, disconnect the car’s battery.
  • To prevent eye injuries, put on safety glasses.
  • Follow the instruction manual properly.

Now, follow these step-by-step processes to take action. 

  • Step 1- Find the oil pressure sending unit in your vehicle: To find where the oil pressure sending unit is located, consult the service manual of your car. The unit is normally situated next to the oil filter or pressure gauge on the engine block.
  • Step 2- Disconnect the battery: To prevent electrical shock, disconnect the car’s battery before starting work.
  • Step 3- Remove the electrical connector: The electrical connector must be carefully removed from the oil pressure-sending device using pliers.
  • Step 4- Take off the old oil pressure sending unit: The oil pressure sending unit should be gently removed using a wrench or socket set. Do not harm the surrounding components or the threads.
  • Step 5- Wrap Teflon tape: The threads of the replacement oil pressure sending unit should be wrapped with Teflon tape. This will aid in tightening the seal and avoiding oil leaks.
  • Step 6- Install the new oil pressure sending unit: Carefully insert the new oil pressure sending unit. Use a wrench or socket set to tighten it until it is completely attached in place.
  • Step 7- Reconnect the electrical connector: Gently push the electrical connector back onto the replacement oil pressure-sending unit until it clicks into place.
  • Step 8- Reconnect the battery: Start the engine after reconnecting the battery. Make sure the oil pressure gauge is reading appropriately and check for oil leaks.

Frequently asked questions(FAQs):

Check this section for further information on the oil pressure sending unit issue.

What is the best way to clean an oil pressure-sending unit?

Use a spray can of electrical contact cleaner ( Our pick), or wire brush, or a toothbrush to clean the oil pressure sending unit. Spray the cleaner over the unit and dust off the accumulated debris.

When the oil pressure light is on, is it safe to drive?

No, it is not safe to drive when the oil pressure light is on. The oil pressure light indicates that your car is running at a low oil level. The engine won’t get enough lubrication if you drive your car with the oil pressure light on, which could lead to overheating, quicker wear and tear, or cause the engine to seize up. 

What impact does oil viscosity have on the oil pressure-sending unit?

If the oil viscosity is too high, the oil won’t flow through the engine as smoothly, and the oil pressure could be too high. It causes the oil pressure sending unit to read a higher pressure than is actually present in the engine. This may cause the dashboard gauge to display inaccurate results. Low oil viscosity will have the opposite effect. 

Bottom Line

To sum up, the oil pressure-sending unit is an important part of an automobile’s engine. This aids in monitoring the oil pressure to make sure the engine operates smoothly and effectively. Knowing its working principle, location, and how to remove and install it will help you in many ways.  

You can help prevent engine damage to your car by being aware of the signs of a bad oil pressure sending unit and taking the necessary safety precautions. You can easily replace this if you know how to replace it. By the way, it’s essential to have this unit inspected and fixed by a qualified mechanic to prevent further damage to your engine.

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