4 Warning Signs of a Bad Oil Pressure Sending Unit

An oil pressure sending unit controls either the oil pressure light or gauge in your dashboard. When the oil pressure sender unit detects oil pressure in the vehicle, a switch trips, and then two things could happen: either the light will shut off or the gauge will become active.

Basically, the oil pressure sending unit is what sends the oil pressure information to the car’s computer, which then controls the related lights and gauges in your dashboard.

A faulty oil pressure sending unit can result in inaccurate oil pressure readings and warnings. So, it is important to recognize the signs of a sending unit that needs to be replaced.

Some of these repairs are an easy task for a seasoned DIYer and will not require a costly visit to a mechanic or auto dealer shop.

Type of Oil Pressure Sensor Units

There are three types of oil pressure sending units.

• Output Side
• Screw-In
• Electrical Voltage Output

All three connect to a light on the instrument panel, though they send their signal in different ways. Sender units are set to trigger a light when the oil pressure is below a safe level for use.

Since the oil pressure is related to the engine revolutions per minute (RPM), this light will come on at low idle speeds and gradually turn off as the RPM increases.

How Much Does One Oil Pressure Sending Unit Cost?

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The cost of the oil pressure sending unit depends on the automobile and the model, as well as what is being replaced. When in doubt, contact your car's manufacturer. Oil pressure sending units can cost anywhere from $30 on the low end to more than $100.

You can find oil pressure sending units at auto parts stores or online parts stores. You can also buy them directly from your car dealer. Where you decide to shop for your oil pressure sending unit depends on your budget and the urgency of the replacement.

Never wait too long to buy one if the unit needs replacement, as the delay can compromise your vehicle’s safety. If the specific oil pressure sending unit you need for your vehicle is rare, this may increase the time between ordering and getting one as well.

Avoid driving your car until you fix this problem, since operating with low oil can be dangerous.

Signs of a Bad Oil Pressure Sensor

1. Check Engine Oil Light Remains On

First of all, you should always check your engine oil when the warning light comes on, even if you’re sure it is completely full. Oil could be leaking from your engine, which is a more immediate, potentially costly repair.

If you've checked the level of your car's engine oil and it is full, but your car's engine oil light is still on, your sending unit may be indicating a false positive, in which case it will need to be replaced.

2. Oil Pressure Reported as Extremely High or Low

If your car's dash is equipped with an oil pressure gauge, look for signs of extremely high or low oil pressure levels.

It's not uncommon for some older vehicles to have low oil pressure when the car is first started. However, if the oil pressure gauge continues to show a low pressure reading even after the car engine is warm, and you can't see any other problems, the culprit may be a defective oil pressure sending unit.

The same would be applicable if the gauge reports very high oil pressure levels as soon as the car's engine is started. Keep an eye on what happens after the car is running for a few seconds.

When an engine is idle, it is normal that the oil pressure will be low, so your sensor will have a low reading in this circumstance as well. This means that your oil pressure sensor light should not be coming on at this time, and if it does, there is definitely something wrong with it. Still, it's best to make sure.

Park your car someplace safe and out of the way to check your oil level immediately. Make sure it's within the minimum and maximum levels of your dipstick; anything below or over the limit is bad for your engine.

3. Oil Pressure Reporting Erratically

Erratic reporting is perhaps the most telltale sign of a malfunctioning oil pressure sending unit. If your oil pressure gauge or engine oil warning light has very sporadic behavior—such as the gauge moving from low to high or high to low randomly or the light coming on and off frequently—you can be sure there’s a problem with the sending unit.

If you have an oil pressure sensor light that keeps coming on even if you have just filled up your oil to the optimal level, then there's a good chance that it's the oil pressure sensor itself that’s the problem. Or, if the light is coming on and off while you are driving, it's most likely a faulty sensor.

In order to make sure, always check your oil whenever the light comes on again. If the oil level is still up to the desired level, then you know it’s time for an oil pressure sensor replacement, which is far better than engine repairs.

It will only cost a few dollars to replace a sensor instead of an engine, which is a much more expensive fix, and one your will likely need a mechanic to do for you.

4. Noises

If your oil pressure sensor light comes on and is accompanied by a strange ticking noise coming from the engine, it would be best to pull over to the side of the road, or your driveway if you haven't yet left, and stop your car as soon as possible.

The ticking sound is usually not indicative of a bad sensor; rather, your sensor might be telling you that you are running dangerously low on oil.

If you have just filled up your oil before leaving the house, there might be a leak in your oil line causing the levels to drop. To see if this is the case, check under the car and the road your car just passed. If your car is still parked, look beneath it and see if there are any oil marks.

You should also pop your hood and check the oil to see if the oil level has significantly decreased since you last filled it. If any of this is the case, it means your oil pressure sensor is working just right, and instead, you have an oil leak that needs repair. Do not wait to do this. The oil leak should be fixed right away.

What Causes an Oil Pressure Sending Unit to Go Bad?

Oil pressure senders tend to fail because of loose or damaged connections in their wiring.

Troubleshooting the Oil Pressure Sending Unit

To troubleshoot the oil pressure sending unit, first unhook the wire going to the unit and ground it with the key on. The gauge should rise to the highest point. If it does, everything is still good. You can also screw the gauge in its place and read the oil pressure.

Oil Pressure Sending Unit Replacement Steps

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.

Conclusion

Faulty readings for your engine oil can be hazardous since you’ll never know if or when your engine oil is truly low. We recommend that you repair it quickly when an issue arises.

Make sure you are also doing other regular maintenance on your car. This will increase the life of your car and ensure that issues are caught early on. A car is the biggest purchase many will ever make, so make sure that you are keeping it in the best shape possible.

Bad Oil Pressure Sending Unit FAQ

What happens when oil sending unit goes bad?

Usually, the check engine light will come on when the oil sending unit goes bad. This will also happen when your oil pressure is low.

Will oil pressure sending unit cause low oil pressure?

A malfunctioning oil pressure sending unit will not cause low oil pressure but it may not alert you when oil pressure is low, which can lead to severe engine problems.

What does the oil pressure sending unit do?

The oil pressure sending unit triggers your warning light to let you know when oil pressure is low. This is a necessary warning symbol because maintaining the correct oil pressure is essential for your vehicle's overall functionality.

How long can you drive with a bad oil sensor?

You can drive with a bad oil sensor because this device by itself does not affect the vehicle's performance. The oil sensor tells you when you need to be aware of low oil pressure, which means you will not get this warning when the sensor is bad.

Having low oil pressure can cause engine problems and can ultimately cause the engine to lock up.

How much does it cost to replace oil pressure sending unit?

Oil pressure sensors cost around $65, while the labor costs up to $100, so the total price of installing a new oil pressure sending unit will be upwards of $150.

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