5 Symptoms of a Bad Oil Pressure Sensor or Switch
Your car’s oil pressure sensor is one of the most important sensors in your car, yet most drivers are unaware of the warning signs of a faulty sensor. Ignoring these symptoms can lead to complete engine failure and thousands of dollars in repair costs.
In this article, we’ll focus on the most common symptoms of a bad oil pressure sensor or switch, helping you identify the problem early and avoid costly damages. An immediate replacement is much cheaper than a replacement.
How an Oil Pressure Sensor/Switch Works
The primary role of the engine oil pressure sensor is to monitor the oil pressure in your vehicle and send this information directly to the instrument cluster or instrument panel. If your vehicle has an electronic control module (almost all vehicles do), the oil pressure switch sends this information to the module where it is calculated.
The calculated information is then sent to the instrument cluster or instrument panel to activate the engine oil pressure warning light or oil pressure gauge.
Symptoms of a Bad Oil Pressure Switch or Sensor
If there is a problem with the oil pressure sensor, the engine oil pressure light will usually be on. It may also cause the oil pressure gauge to give an inaccurate reading. Below are the four most common signs of a faulty oil pressure switch or sensor.
1) Oil pressure light flashes repeatedly
If the oil pressure sensor is not working properly, the oil level indicator on the dashboard may flash. This may cause the driver to panic, thinking that the oil level is too low, which may lead to engine damage if this is true.
To determine if this is a real warning, you should manually check the oil level to see if it is too low. If not, the oil pressure sensor may be faulty and should be replaced immediately.
2) Incorrect Oil Pressure Gauge Readings
- If you are driving an older car, it may have some kind of mechanical gauge that calculates the oil pressure.
- If the oil level is normal but the gauge shows zero, it means that the oil pressure sensor is faulty or has a problem with the connection and needs to be replaced.
- If you drive a modern vehicle, your oil pressure gauge is likely electronic, sending an electronic signal to get a reading.
- If the oil pressure sensor on a modern car fails, the gauge will show odd readings or show a full or zero value. Check the sensor wiring and replace if necessary.
Never assume your engine oil level is low without physically checking the dipstick. Failure to do so could result in excess oil in the engine, which could cause other issues, such as elevated oil pressure.
3) Check Engine Light Comes On
A failure in the sending unit can cause the check engine light to come on and trouble codes such as:
P0520 (general sensor failure)
P0521 (inconsistent readings)
P0522 (low oil pressure)
P0523 (high pressure)
While these codes can help diagnose the problem, it is important to have a professional mechanic inspect your vehicle to confirm the problem and make any necessary repairs.
4) Oil Pressure Light Comes On
The best way to test if the sensor is bad is to look at the oil pressure gauge light. If the low oil pressure warning light comes on when the engine oil level is normal and the engine is running smoothly and quietly, it is likely that the oil pressure sensor is faulty. A defective sensor will give you erroneous readings.
If the oil level is normal but you hear grinding, clicking, or other abnormal noises coming from the engine, then you may have an actual oil pressure problem, such as a bad oil pump, and the sensor is just working. At some point, these values will significantly exceed normal values and the warning light will come on. At this point, the sensor should be replaced so that you can be constantly aware of the oil pressure.
5) Abnormal Engine Sounds
While a faulty oil pressure sensor can cause a false alarm, actual engine sounds combined with an oil pressure warning often indicate a real problem.
Listen for any clicking, knocking, or grinding noises, especially if they get louder or faster as engine RPMs increase. These abnormal noises, especially when they occur with the oil pressure light on, are an indication of insufficient lubrication due to low actual oil pressure.
If you hear these sounds along with the oil pressure warning, you should check your oil level immediately. If the level is normal, you should schedule a service appointment as soon as possible to avoid potential engine damage.
What to Do If You Suspect a Bad Oil Pressure Sensor
Check the Oil Level – Use the dipstick to manually verify your engine oil level. If it’s low, top it up and see if the problem goes away. If the level is normal, proceed to the next steps.
Inspect the Sensor and Wiring – Locate the oil pressure sensor (usually in the vicinity of the oil filter) and check for visible damage, corrosion, or loose connections. Make sure that the wiring harness is securely attached.
Use an OBDII Scanner – Connect a scan tool to check for error codes. Look for codes related to oil pressure such as P0520, P0521, P0522, or P0523.
Test the Sensor (if possible) – If you’re comfortable and have a multimeter, test the sensor’s resistance. Consult a model-specific service manual for the correct procedure and specifications.
Monitor Engine Performance – Pay attention to any unusual engine noises, loss of power, or even a change in fuel efficiency, as these could indicate a real oil pressure problem rather than just a sensor issue.
Check the Oil Pressure Gauge – If your vehicle has an oil pressure gauge, observe its behavior.
Perform a Road Test – Drive the vehicle and note when the oil pressure light comes on or when you feel vibrations. This information can be valuable for diagnosis.
Get Professional Help – If you’re unsure about any of these steps, or if there’s no change to the problem after you’ve completed the steps, seek help from a qualified mechanic. They have the tools and knowledge to perform advanced diagnostics to confirm whether the sensor needs replacement or if there’s an underlying oil pressure issue.