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Oil Pressure Sensor (4 Symptoms, Testing & Replacement Cost)


Every engine has oil circulating from the oil pan through the oil filter and throughout the engine to lubricate moving parts and also cool the motor. If your car is low on oil or your oil pump fails, your motor can seize up, leading to very expensive repairs.

Car manufacturers install an early warning system called an oil pressure sensor. If the oil pump fails or you are low on oil in your car, the oil press will fall, and the sensor will alert you that there is a problem. Oil pressure sensors also fail due to oil sludge, internal mechanical issues, and electrical failures.

When your check engine light turns on, the oil light comes on, or the oil pressure gauge indicates an issue with the oil in your engine, attend to the problem immediately to avoid potentially costly repairs to the motor if it is running low on oil. However, in many situations, mechanics usually replaced the sensor to correct the problem.

What are oil pressure sensors?

Brand New Oil Pressure Sensor

An engine oil pressure sensor is a small unit located on the side of the motor that measures the oil pressure in the engine and reports the measurement to your dash in the form of oil pressure on a gauge or an oil light on the dash.

The sensor is normally closed when there is a pressure drop and opens once pressure is applied. There must be sufficient pressure to open the unit. When the sensor opens, it completed the electrical circuit, and your oil light on the dash remains off.

The oil pressure sensor is relatively inexpensive to replace. If the oil light illuminates, listen to your engine for increased noise caused by lack of lubrication. This is a quick way to tell if the oil pump has failed, which is unusual or if the oil pressure sensor has failed.

Oil pressure sensors can be located anywhere on the engine. Some are easy to access, while many are difficult to locate and remove. You may have to remove other components just to reach the oil pressure sensor.

How does an oil pressure sensor work?

Oil pressure sensors are attached to the engine, and oil is fed into the unit. As the oil pressure builds, a small plunger in the unit opens, causing an electrical connection to open, which keeps the oil pressure light on your instrument cluster from turning on.

If the sensor is filled with sludge or mechanically breaks down internally, the plunger cannot operate in the normal manner, and your oil pressure light may turn on. If you have a gauge on your dash, the plunger causes resistance to increase as the oil pressure increases, causing the gauge reading to display a corresponding oil pressure.

Oil pressures should be higher than 10 PSI at the start and in the idle mode. As engine RPM increases, the oil pressure should also increase. Only cars equipped with an oil pressure gauge located on the dash will display this information. Most cars come with an engine oil light and only illuminate if the oil pressure does not meet the specifications of the oil sender unit.

Where is the oil pressure sensor located?

Location Of The Oil Pressure Sensor

Oil pressure sensors are located in various locations depending on the age of the vehicle, the make, and the manufacturer. Check engine specifications and diagrams to locate your oil pressure sensor for your make and model. These specifications can normally be found online.

On older vehicles, the oil sending unit may be easy to locate and remove. Many modern car compartments are filled with a variety of equipment such as air conditioning and environmental control systems that get in the way of locating the oil pressure sending unit.

There are also many sensors in modern cars. Make sure you locate the right unit. The oil pressure sensor is usually located on the engine block.

You may have to remove some components to access the unit. Remove these components carefully and take notes or add markings to help in the reassembly of the components you needed to remove.

 Symptoms of a Bad Oil Pressure Sensor

The symptoms of a faulty oil pressure sensor can also be symptoms of other problems related to the oil circulation system within your engine. For example, low oil in the engine can cause low pressure and the oil light to illuminate.

The warning lights can also illuminate, indicating the oil pressure sensor has an issue, which could be caused by oil sludge buildup or a bad electrical connection. We will explore these issues more.

#1 The engine oil pressure light turns on

Whenever the oil warning light turns on, the first step is always to check the oil level in your car, especially if there are signs of an oil leak. If the oil is at the proper level, listen to the engine. If the car does not produce strange noises, there is a good chance that the oil pump is working and circulating oil and the sensor has malfunctioned.

#2 The low oil light blinks continuously

A blinking oil warning light indicates that the oil pressure is rapidly changing every few seconds.

Always check the oil level in the engine first. If the oil level is fine, the oil pressure could be quickly changing due to internal oil pump problems and circulation.

#3 The oil pressure gauge is giving the wrong reading

The oil sender unit can become stuck due to a buildup of sludge in or around the unit. This can cause inaccurate readings of the oil pressure. Check the oil level, have the engine flushed and add new oil and filter. Then observe the oil pressure after the oil change. You may still need to install a new oil pressure gauge after you have replaced the oil.

#4 Vehicle is making strange noises

When you car or truck begins to make weird noises such as knocking or tapping, this can be an indication of a problem with the with the sensor or a leak.

Your car may need a new pump or switch immediately to avoid potential damage. Make sure you also replace the oil pick up tube if you need to replace the pump. Having proper lubrication makes a huge difference.

How to test an oil pressure sensor?

Testing bad switches can be accomplished in one of three ways:

Testing for Continuity: Remove the oil sensor from the engine block, clean it up, and test for continuity. Use an ohmmeter to check the resistance in both the open and closed positions. The sensor is normally closed, providing a short when measured. There will be a resistance measured when it is open. Obtain specs from the manufacturer.

Testing the oil pressure: Attach an oil pressure gauge to the port where you removed the sensor. Be careful to avoid damaging the thread of the port when connecting the gauge. Start the car. Once the engine is warm, you should read above 10 PSI and up to 40 or 50 PSI. The pressure should also remain stable.

Testing the sensor for proper operation: Attach an air pressure hose to the port end of the sensor and release air. You should be able to read on the ohmmeter a change in resistance when the air is released.

What does the oil pressure sensor replacement cost?

The cost to replace the oil pressure sensor depends on the make and model of the vehicle. The part or sensor is only about $35 to $60. The labor involved is dependent on where the oil sensor is mounted and what has to be removed to get to it.

Some are mounted within easy reach on the engine block. All that is needed is an appropriately sized wrench to unscrew it and to install a new one.

On our modern vehicles with air conditioning units and environmental control systems installed in and around the engine compartment, access is often more difficult. Often several other items must be removed to access the sensor.

Once the new sensor is installed and the parts that were removed are re-installed, you can test the engine and confirm that the oil pressure is operating properly. Of course, this extra labor adds to the cost. Labor can cost from $120 to $160.

How to Change an Oil Pressure Sensor

Turn the engine off and locate the oil pressure sensor. It will be on the side of the engine block with an electrical wire attached. You should have a new unit on hand, and you can use this unit to determine what size of socket or wrench to use.

Using the socket, remove the bad sensor and clean up any oil that may drip out. It is a good idea to place a drip pan under the engine to catch any oil that drips out. Install the new sensor.

Be careful to twist the sensor until it grabs the thread without forcing it. Damaged thread on the engine block can get very expensive to repair.

Use the socket to tighten the oil sending unit and connect the electrical cable to the sensor. Start your car to confirm that your oil pressure light turns off or your oil gauge provides a correct reading.

What happens when the oil pressure sensor goes bad?

If you are using an oil gauge, the gauge will provide inaccurate readings, usually low oil pressure. If there is no gauge, the oil pressure warning light will turn on, and the check engine light may also illuminate. A bad oil sensor leaves you wondering if the oil pressure is low or if the level of oil in the engine low or is it a bad sensor.

The first step is to check your engine oil level. If it is at the correct level, listen to the engine while it is running. A smooth-running engine running quietly is not having oil circulation problems. In most cases, it is typically a faulty oil pressure sensor that has malfunctioned.

There is also the possibility that the electrical cable leading from the sensor to the electronic control module has been damaged or come loose. This can easily be checked before doing more tests as outlined previously. In many cases, the oil pressure switch goes bad and must be replaced.

Is it OK to drive with a bad oil pressure sensor?

It can be ok to drive with a failing oil pressure sensor. However, drivers should have this repaired as soon as possible to avoid damage to the engine. With no information about the oil pressure in your car, the driver could be damaging the engine without knowing.

There are several steps to manage the risk if your sensor is malfunctioning and you cannot get to a mechanic for repairs.

Check the level of oil in the engine. If it is at proper levels, as indicated on the dipstick, you can be sure that there is sufficient oil in the engine.

Next, listen to the car while it is running at idle. If it is running quietly and smoothly, not overheating, there is a good chance that there are no issues with oil circulation in the engine, and it is safe to drive it. Nevertheless, have your bad sensor checked and replaced as soon as possible.

How do you know if your oil pressure sensor is bad?

There is no way to know if your oil sending unit is bad without testing it. Sufficient oil in the engine and a quiet-sounding car are indicators that you do not have low oil in the engine and that you have sufficient oil pressure to lubricate the engine components.

Otherwise, it would run noisy, and you would hear the valves and pistons making more noise than usual. That leaves the sensor and the wiring connecting it to the car’s computer system.

Check the wiring to make sure that there is a secure connection. The next step is to remove the sensor and test the oil pressure with an oil pressure gauge or try testing the sensor itself.

If the oil pressure gauge reads normal oil pressure, then you can be pretty certain that the sensor has failed or been clogged with sludge. Either way, for the relatively low cost, replacing the sensor makes sense now that you have removed it.

Sometimes the lights can turn on due to false readings. Most f the time, this is due to a problem with the mechanical gauge on the instrument panel. You will need to double-check that the electronic signal is not producing an inaccurate reading.

Will my car run without an oil pressure sensor?

The quick answer is yes, your car will run with a failed oil pressure sensor. However, if it is working correctly and the oil pressure is low, or you have low oil in the engine, you risk damaging the engine components and a costly repair.

Before running your engine with a bad sensor, check your oil level to ensure there is sufficient oil in the engine. Next, start the car and listen carefully to the engine while it is idling.

It should sound quiet with no slapping of metal against metal sounds. If you hear these sounds, shut it off immediately and have it towed to a repair shop. The oil pump may have failed, and oil is not lubricating the engine.

While your car can be driven without an oil pressure sensor working properly, there is no information available to you to let you know that the engine is running properly with sufficient oil. We recommend you arrange for repairs as soon as possible.


The oil pressure warning light illuminates in your dash to let drivers know there is a problem with the oil lubrication system in the car. It could indicate:

  • Low oil levels
  • Low pressure
  • Malfunction of the sensor
  • Damage to the wiring harness
  • Strange readings

Make arrangements to have your car checked immediately before expensive engine damage occurs. Listen to the sound of the car. It would be much noisier if the lubrication system failed.

Check that the oil level is within proper levels. If it sounds normal and there is sufficient lubricant in the engine, you may have a malfunctioning sensor, and the check oil light continues to illuminate until it is replaced.

Nowadays, if there is something wrong with your modern car, the oil sensor will send a signal to the electronic control module that calculates it. However, your sensor or switch needs to be in working order if you want your car’s computer to regulate the oil flow and temperature.

For more information search on the owner’s manual, and if you continue to have the same problem try a local repair shop. Every time you see a leak don’t just assume is the sensor, it can also be a leaking hose or gasket.

Last Updated on: July 14, 2022

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