What Is An Oil Pressure Sending Unit?
An oil pressure sending unit singles the warning light if there’s a drop in oil pressure. If it breaks, you could face serious engine damage.
Written by Patrick Price
Reviewed by Melanie Reiff
The oil pressure sending unit is an important component in any vehicle and is responsible for monitoring the oil pressure and alerting the driver if there’s an issue. Without a working sending unit, you would have no way of knowing if your oil pressure was too low, which could lead to catastrophic engine damage.
If your sending unit is bad, you should get it replaced as soon as possible. Otherwise, you could have a serious oil pressure problem and not even know it. If you’re not sure whether or not your sending unit is bad, don’t worry. This article—brought to you by
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—will explain all about what an oil pressure sending unit is, how it works, and how to tell if yours is faulty. Jerry sends free alerts to keep your car up-to-date so you can avoid costly repairs
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What is an oil pressure sending unit?
An oil pressure sending unit—sometimes called an oil pressure switch or an oil pressure sensor—is a device that monitors your engine oil pressure and alerts you if there’s an issue.
For an internal combustion engine to function, it needs to be cooled and lubricated by motor oil, so oil is constantly circulated to every part of your engine. To maintain this vital circulation, your engine oil must be pressurized.
The oil pressure sending unit helps make sure that the pressure doesn’t get too low, triggering the oil pressure warning light to come on if the pressure drops.
The sending unit is comprised of two parts—the switch and the diaphragm. If everything is normal, the oil pressure keeps the diaphragm pushed against the switch. The diaphragm will relax if the pressure is too low, releasing the switch and turning the warning light on. This will give you time to shut off the engine before your engine is damaged.
Do you have a bad oil pressure sending unit?
The oil pressure sending unit is vital for keeping tabs on your oil levels. If it’s not working, you could be driving with low oil pressure and not even know it—that’s why it’s so important to know if your sending unit is bad.
Signs that your oil pressure sending unit isn’t working
There are a few common symptoms that give away when your sending unit has gone bad. Familiarize yourself with the list below—that way you’ll know what to watch out for.
- If the oil pressure warning light is on, but your oil is at the correct level and your engine is functioning normally, it could be a sign that you have a bad sending unit
- If your car has a real-time oil gauge, and that gauge is showing erratic or strange readings (while your engine is running normally), then you probably have a bad sending unit
- If your oil pressure warning light is blinking or turning on and off inconsistently, then you probably should check your sending unit
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How to test your oil sending unit
If you notice any of the signs that can indicate a faulty oil pressure sending unit, you should test your unit as soon as possible. Here’s how you can do so:
- Step 1: Before testing your sending unit,open the hoodand double-check that your motor oil is at the proper level. If not, add some oil and check to see if the warning light has turned off
- Step 2: Locate the oil sending unit (usually attached to the engine block near the oil filter) and unscrew it
- Step 3: Attach anoil pressure testing gauge—which can be purchased at most auto parts stores—in place of the sending unit
- Step 4: Start the engine and allow it to idle for a few minutes while you keep an eye on the oil gauge. If the pressure stays within the normal range (usually between 40 and 60 psi, depending on your car’s make/model)
- Step 5: If your sending unit was alerting you that your pressure was low and the test gauge indicated that it was normal, then you’ll know that your sending unit is bad and needs replacing
How to replace a bad oil pressure sending unit
Replacing an oil pressure sending unit is a relatively straightforward process, but it does require some special equipment and knowledge—so, it’s usually best to have a professional mechanic do it for you.
When you take your car in to have the sending unit replaced, these are the basic steps that the mechanic will follow:
- Disconnect the battery (negative cable only) and raise the vehicle on jack stands—making sure to engage the parking brake
- Remove the old sending unit by disconnecting the electric wire and unscrewing the unit with a sensor socket and a ratchet
- After applying sealant tape (if necessary), install the new oil pressure sending unit in place—first, screw it on by hand and then tighten it with a wrench
- Attach the electric wire to the new sending unit
- Lower the car and then reconnect the battery
And that’s how it’s done! The whole process should take your mechanic 15-60 minutes and cost between $50 and $250.
Finding affordable car insurance
Replacing an oil pressure sending unit is relatively fast and cheap. Unfortunately, the same is not true for every automotive issue that you’ll run into. For more serious trouble, you’ll need a quality
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FAQs
Is an oil pressure sending unit the same thins as an oil pressure switch?
Yes. Well, more or less. The oil pressure switch is just one of the main components that comprise an oil pressure sending unit. While not technically synonymous, however, the two terms are regularly used interchangeably.
Can you drive with a bad oil pressure sending unit?
While you can drive with a bad oil pressure sending unit, it is not a good idea to do so. Without a working sending unit, you would have no way of knowing if your oil pressure is in the popper range.
You could drive without one and have nothing go wrong. On the other hand, if your oil pressure does drop, you wouldn’t know until it was too late and your engine was already damaged beyond repair.
How much does an oil pressure sending unit replacement cost?
An oil pressure sending unit replacement typically costs between $50 and $250, depending on the quality of the replacement unit and the hourly rates of the mechanic your hire.
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