The engine oil pressure sensor, also known as the oil pressure switch or oil pressure sending unit, is a small component installed between the oil filter and your car’s oil pan.
The sensor plays a vital role in making sure your engine functions well.
It monitors the oil pressure in the car’s lubrication system and reports to the Electronic Control Unit when it detects low oil pressure.
This Article Contains:
- 3 Signs of a Bad Engine Oil Pressure Sensor
- How to Diagnose a Faulty Oil Pressure Sensor
- 4 FAQs on Engine Oil Pressure Sensors
Let’s get started.
3 Signs of a Bad Engine Oil Pressure Sensor
Knowing when your car’s oil pressure sensor starts acting up can save you plenty of time, money, and possibly your life.
These warning signs can either indicate that your oil pressure switch needs a replacement or that something is wrong with the parts it’s connected to, like the oil pump, gauge, and filter.
The simplest way to figure out if your oil pressure sensor is in good condition is to look at your car’s dashboard.
Here are three visible warning signs that your oil pressure sensor is faulty:
1. Inaccurate Reading From the Oil Pressure Gauge
The first and obvious sign that your engine oil pressure sensor is not working properly is when the oil pressure gauge gives a wrong reading. A faulty oil sensor is considered a typical cause for incorrect readings.
The gauge pointer corresponds with the oil pressure in the car’s oil pan. When you have a faulty oil pressure sensor, sometimes the pressure gauge pointer will either be stuck at one end, or the oil gauge will only work at irregular intervals.
2. Oil Pressure Warning Light is On or Blinking
Normally, the oil pressure warning light will turn on when your car is running low on fuel, or you have an oil leak.
A faulty oil pressure sensor can falsely trigger a low oil pressure condition, which turns on the oil light. If the oil pressure sending unit is damaged, it can also cause the oil pressure light to blink on and off.
To determine whether the warning light is triggered by actual low oil pressure or a faulty oil pressure switch, your mechanic will check the engine oil level in the oil pan. If the oil level is normal, then there’s a chance that you need to replace the oil pressure sensor.
3. Illuminated Check Engine Light
The check engine light is a warning light that’s turned on when there’s a problem with any engine component. This also includes the engine oil pressure sensor.
The only way to know if a bad oil pressure sensor is the cause is by bringing your car to the mechanic for a check-up. Your mechanic will connect a Diagnostic Trouble Code (DTC) scanner to the car’s Electronic Control Unit and run a diagnostic scan.
If a faulty oil pressure sensor is the cause of the illuminated warning light, then one of the following OBD codes will likely show:
- P0520: General physical problems related to poor engine performance
- P0521: General Internal problems causing low oil pressure
- P0522: Specific internal issues causing low oil pressure
- P0523: Specific internal issues causing high oil pressure
Note: Contact your mechanic to get your car towed or let them come to you, if this warning light is on.
If the light turns on when you’re on the road, try to find a safe place to park and shut the car off immediately, air conditioning included. This helps to minimize the chance of costly internal engine damage.
Now you know the signs of bad oil pressure sensors, let’s see how to go about a diagnosis.
How to Diagnose a Faulty Oil Pressure Sensor
When figuring out whether a faulty oil pressure sensor is the root cause, there are a few steps to follow.
Before beginning, your car should be parked on a flat surface, and that the engine is cold. Doing so prevents your hands from getting burnt.
NOTE: If you’re unfamiliar with car parts, always get an auto professional to perform a diagnosis.
1. Check Engine Oil Level and Condition
First, verify the oil level in your engine by pulling out the dipstick from the tube. Wipe it clean and reinsert it into the tube to observe the markings on it. If the engine oil level is below the top/full marker, then low oil pressure is causing your engine trouble.
Next, observe the oil’s condition:
- Regular engine oil should be dark brown or black
- A light and milky oil appearance means that your coolant has leaked into the engine
- If there are metal particles in the oil, then it could be internal engine damage
If you’re doing this at home, and find any of the conditions above, DO NOT drive your car! It’s best to get your car towed or contact a mobile mechanic to prevent further damage to the engine.
2. Check the Wiring to the Sensor
If the oil level and conditions are normal, the next step is to check the sensor’s wiring. Conduct a visual inspection to look for damaged or poorly connected wiring.
3. Check Actual Oil Pressure
The last step before you can confirm a faulty oil sending unit is to inspect the actual oil pressure in the engine. You’ll need an oil pressure gauge for this.
Remove the oil pressure switch and install the oil pressure gauge with the adaptor to the engine. Turn on the engine, let it warm up to a specific temperature, and maintain a steady RPM before taking a reading on the pressure gauge.
Note: Different engine models and make have different manufacturing settings to check their oil pressure.
If the gauge gives a low oil pressure reading when the engine is running, it could be an internal issue with the engine’s lubrication system or the oil is too thin for your engine. It can also indicate a blocked oil filter, as it causes slow oil flow into the engine, thus creating low pressure.
If the oil pressure is within the expected values on the oil gauge and there are no issues with the wiring, there’s a high chance you have a bad oil pressure sensor or switch.
You’ve got the basics of how to diagnose a bad oil pressure sensor. Let’s answer some related FAQs next.
4 FAQs on Engine Oil Pressure Sensors
Here are some commonly asked engine oil pressure sensor related questions:
1. How Does an Engine Oil Pressure Sensor Work?
Oil pressure sensors exist in two types:
- A simple switch that leads to an open circuit when it detects the minimum required oil pressure (for modern car)
- A sensor that measures the actual oil pressure in the engine (older car)
Both types monitor the engine’s oil pressure and transmit information to the oil pressure gauge on the dashboard.
Here’s how the more common switch type works:
When you turn on the ignition, and the engine is still off, there is no oil pressure. The switch remains closed, causing the oil pressure light to turn on, and the gauge reader is at 0.
But when you start the engine, the oil starts flowing into the engine’s lubrication system. The flow of engine oil from the oil pan to the engine block produces oil pressure, which is then detected by the oil pressure sensor.
The sensor picks up the pressure in the lubrication system and opens the switch (open circuit). It transmits the readings to the car’s processing unit and the instrument cluster panel. The low oil pressure light then turns off.
2. Is Driving With a Bad Engine Oil Pressure Sensor Safe?
Driving isn’t recommended when you have a bad oil pressure sensor. You shouldn’t take it lightly, even if you’re confident it’s just an oil pressure sensor problem.
Maintaining the correct oil pressure in your engine is critical to keep it functioning. A bad oil pressure sensor can give the wrong oil pressure readings. You won’t notice if the oil pressure is too low or too high and risk damaging the engine altogether.
You’ll also put your safety on the line if you persist in driving with a bad oil sending unit.
3. How Much Does it Cost to Replace an Oil Pressure Sensor?
Depending on your car’s model and make, the price of replacing your oil pressure sensor will differ. Typically, an engine oil pressure sensor will cost about $60.
Labor charges also differ depending on your location and how long the replacement takes.
4. How Often Should I Replace My Oil Pressure Sensor?
There’s no specific schedule for replacing your oil pressure sensor. There is also no exact way to predict when the sensor might fail. Depending on how you care for your vehicle, the engine oil pressure switch can last a long time.
If you do a lot of harsh driving — heavy and repeated sudden brakes, driving in stop-and-go traffic, then you should get your engine’s oil system frequently checked.
You can also prevent your oil pressure sensor from acting up by replacing your engine oil and oil filter according to schedule.
The recommended oil change schedule for a modern car is twice a year, regardless of mileage or even if you barely drive. Like any other oil, engine oil can degrade in six months. Driving with degraded engine oil can lead to more serious problems in the long run.
On the other hand, replacing the oil filter on your engine should be done after every second oil change. For example, if your oil change follows a 3,000-mile cycle, the oil filter should be changed every 6,000 miles.
The engine oil pressure sensor or switch is a crucial component to keep your car’s engine running. A faulty engine oil pressure switch can cause severe damage to your engine if left unattended.
The easiest way to prevent your oil pressure sensor from failing is to ensure regular servicing. What better way to do that than with RepairSmith?
RepairSmith is a mobile auto repair and maintenance service. We offer a wide range of repair and replacement services with convenient online booking.
Contact us today if you need an oil pressure sensor replacement, and we’ll send our best mechanics to your location.