Your car’s oil pressure sensor is one of the more important sensors in a car, yet most drivers don’t know the warning signs of one that’s failing. Ignoring these symptoms can lead to complete engine failure and thousands of dollars in repair bills.
This article reveals the most common symptoms of a bad oil pressure sensor or switch, so you can catch problems early and avoid costly damage. Replacing it now will be a whole lot cheaper than the alternative.
How an Oil Pressure Sensor / Switch Works
The main job of an engine oil pressure sensor is to keep track of the oil pressure in the vehicle and then transmit this information straight to the combination meter or the instrument panel.
If the vehicle has an electronic control module (almost all do), then the oil pressure switch will send this information to the module where it can be calculated.
After it is calculated, the information gets sent to the combination meter or instrument panel so that the engine oil pressure warning light or the oil pressure gauge can be activated.
Symptoms of a Bad Oil Pressure Switch or Sensor
If there is a problem with the oil pressure sensor, then this will usually activate the engine oil pressure light.
It could also cause an inaccurate reading to be given from the oil pressure gauge. Below are the four most typical signs of a faulty oil pressure switch or sensor:
#1. Repeated Blinking from the Oil Pressure Light.
Sometimes if the oil pressure sensor is not working properly, there will be blinking from the low oil light on the dashboard.
This could cause a driver to panic because they’ll believe that their oil levels are low, which would end up damaging the engine if it were true.
In order to determine if this is a real warning or not, you should manually check your oil level to see if it is low. If it isn’t, then it is likely you have a faulty oil pressure sensor and you need to replace it right away.
#2. Wrong Reading Shows on the Oil Pressure Gauge.
If you are driving an older vehicle, then it likely has some type of mechanical gauge that calculates the oil pressure.
Whenever the oil levels are normal but the gauge is showing zero, this means the oil pressure sensor needs to be replaced because it is faulty or there is some type of connection issue.
If you are driving a modern vehicle, then your oil pressure gauge is probably electronic and transmits an electronic signal to get the reading.
Whenever an oil pressure sensor is not working properly in a modern car, it will cause the gauge to have strange readings or it will sit on full or zero. Check the wiring to the sensor and replace as needed.
Don’t assume your engine oil level is low without physically checking the dipstick. Otherwise you may end up with too much oil in your engine which can mean a completely different set of issues in include oil pressure that’s too high.
#3. Check Engine Light Turn On.
If the sending unit fails, it can cause the check engine light to come on and trigger error codes such as:
- P0520 (general sensor malfunction)
- P0521 (reading discrepency)
- P0522 (low oil pressure)
- P0523 (high oil pressure).
These codes can be helpful in diagnosing the issue, but it’s important to have a professional mechanic inspect the vehicle to confirm the problem and make the necessary repairs.
#4. Oil Pressure Light Turns On.
The best way to test if your sensor is bad is through the lights on the oil pressure gauge. If the low oil pressure warning light comes on when they engine’s oil levels are normal and your engine is running smoothly and quietly, then you likely have a bad oil pressure sensor. Anytime this sensor is defective, it will give you false readings.
If your oil levels are normal but you hear grinding, ticking, or other noises from your engine, you have an actual problem with oil pressure such as a faulty oil pump and the sensor is simply doing its job.
Eventually, these readings will go way beyond the normal specifications which will cause the warning light to turn on. At this point, you should replace your sensor in order to stay properly informed of your oil pressure level.
#5. Unusual Engine Noises.
While a faulty oil pressure sensor can trigger false warnings, actual engine noises combined with oil pressure warnings often indicate a real problem.
Listen for ticking, knocking, or grinding sounds, especially if they get louder or faster with engine speed. These noises, especially with an illuminated oil pressure light, suggest insufficient lubrication due to genuine low oil pressure.
If you hear these noises along with oil pressure warnings, check your oil level immediately. If the level is normal, you should make a service appointment ASAP to prevent potential engine damage.
Oil Pressure Sensor Replacement Cost
The cost of replacing a faulty oil pressure sensor in a car can vary depending on a few factors. But on average, replacement cost should be in the range of $100 to $220 in most cases (including labor).
The oil pressure sensor itself can cost between $30 and $100, while labor costs can range from $70 to $120. However, the cost of parts can vary depending on whether you choose aftermarket or OEM (Original Equipment Manufacturer) auto parts.
Additionally, the cost of labor can vary depending on the mechanic’s experience and location. In general, you’ll pay more at a dealership versus an independent mechanic.
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. Erratic readings or a gauge that’s stuck at full or zero could mean you have a faulty sensor.
- 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.