Top 5 Warning Signs of a Faulty Oil Pressure Sensor

Losing engine oil pressure is one of the most serious and potentially damaging issues your vehicle can face. This is why almost every vehicle is equipped with an oil pressure sensor (OPS) and a warning light. In some cars, there may also be an oil pressure gauge.

But what if the oil pressure warning on your dashboard is actually due to a faulty oil pressure sensor? Recognizing the signs of a bad sensor can help you determine the difference.

What Are the Signs of a Bad Oil Pressure Sensor?

Knowing how to tell if an oil pressure sensor is bad can be crucial for maintaining your engine’s condition. So what happens when this part is faulty?

Oil Pressure Warning Light

An illuminated oil pressure warning light is one of the first likely symptoms of a bad oil pressure sensor. Even if the instrument cluster has an oil pressure gauge, on newer vehicles it will also have some type of warning light that will turn on if the oil pressure is perceived to be low.

To confirm if the issue is with the sensor or the engine, note whether the light flickers on and off without any unusual engine noises—this often points to a sensor problem.

Incorrect Oil Pressure Readings

Another common symptom of a malfunctioning oil pressure sensor is inaccurate readings on the oil pressure gauge. But how can you tell if the gauge is wrong? You’ll likely notice other symptoms, such as the ones on this list.

To help diagnose whether the sensor is the problem, a mechanic will typically remove the component, attach a mechanical gauge to the port, and check oil pressure when the engine is cold. They will then monitor it as it warms to operating temperature. If there’s an actual oil pressure issue, they’ll investigate further.

If the OPS is faulty, the gauge may fluctuate erratically, show readings that are too high or too low, or even get stuck at one extreme.

Unusual Noises

Noises, along with low gauge readings, could be indicative of a failed oil pressure sensor. It’s important to note that if you hear sounds that seem to indicate low oil pressure, like timing chain rattle on engines that use an oil-driven tensioner or lifters clicking, you’ll need to check the oil.

If it’s not too low (like a quart low or less), the problem is deeper and needs to be investigated by a mechanic.

Reduced Engine Performance

One thing you may also observe is decreased engine performance. This happens when the oil pressure sensor struggles to send the right signals to the car’s control module. The result is poor engine performance—particularly decreased fuel economy and acceleration.

If the oil pressure is low, the powertrain control module (PCM) or engine control module (ECM) may reduce engine power in an effort to prevent engine damage. On some platforms, the PCM/ECM will literally shut the engine down.

Check Engine Light

Newer cars typically have the vehicle computer or control module monitoring the engine’s components, including the oil pressure sensor. When it detects an issue with the sensor, it could trigger the check engine light and save specific diagnostic codes related to oil pressure and engine problems, such as P0520 through P0523.

These trouble codes can be verified with the help of a mechanic or a specialized OBD-II scanner.

It’s important to get your oil pressure sensor checked if you notice any of these symptoms. An oil pressure warning light won’t always mean that you have low oil pressure. Dodge platforms, for instance, routinely have failed oil pressure sensors even when there’s nothing wrong with the engine oil pressure.

What Does the Oil Pressure Sensor Do?

The oil pressure sensor works with the PCM to monitor engine oil pressure. The latter supplies the sensor with a 5-volt reference and a signal ground, reading the oil pressure through the sensor’s signal wire. If the PCM detects oil pressure that is too high or too low, it sends a command to the Body Computer or Instrument Cluster to illuminate the oil pressure warning light.

The oil pressure sensor itself is a simple device with a small hole at the bottom where it threads into the engine. When pressurized oil pushes on the internal diaphragm, it activates an electrical contact, functioning like an on-off switch. On systems with a light directly connected to the gauge, the sensor threads act as the ground, and the normally closed switch opens when oil pressure exceeds its calibrated threshold.

However, some vehicles, like Fords from 1997 onward, use a normally open switch with a 22-ohm resistor to stabilize the gauge needle in the center. If pressure drops below the threshold, the gauge falls to zero, and the oil light activates.

For systems with transducers, a variable resistor moves the gauge needle to reflect actual oil pressure. More advanced sensors include a potentiometer circuit that the PCM uses to interpret oil pressure through analog signals.

On certain platforms, the PCM also logs this data as a freeze frame parameter, aiding in diagnostics during maintenance or repairs.

Where is the Oil Pressure Sensor Located?

An oil pressure sensor needs to be tapped into the oil gallery to read the pressure being produced by the oil pump. It’s typically located in the cylinder block near the oil filter, although newer vehicles may have it on the oil cooler.

Oil Pressure Sensor Replacement Cost

So how much does it cost to replace an oil pressure sensor? The good news is that these sensors are generally affordable, with the more expensive units ranging between $80 and $100—though often less than that. A word to the wise: Don’t buy the cheapest sensor you can find. Given the low cost of a good sensor, it’s worth spending a few extra bucks.

Oil pressure replacement costs may be relatively low in comparison to many other vehicle parts. However, keep in mind that if you’re having a mechanic perform the replacement for you, the total cost to replace an oil pressure sensor could vary significantly depending on the sensor’s location and how much disassembly is needed to access it.