Oil pressure sensor: what is it and what are the symptoms of sensor failure?

Engine oil is like the lifeblood of every internal combustion engine. However, engine oil serves a number of functions: it lubricates the moving parts of the engine, removes dirt, and helps maintain the engine at the optimal temperature.

Since engine oil has more than one function, the right level of engine oil is crucial to ensure the long-term durability of the engine, but this is not new.

For many years, to check the engine oil level, all you had to do was open the bonnet and use an engine oil dipstick, which gave you a few moments' insight into whether the engine oil level was too low, sufficient, or even too high. However, the growing number of electronic devices in cars is slowly replacing the old-fashioned dipstick with sensors and gauges for engine oil level.

How does an oil level sensor work?

The basic idea behind this device is to ensure that the oil level in the engine is sufficient. Automotive engineers mount this elongated, thin device in the oil pan, where it measures the oil level when the car is stationary and when the car is moving.

In general, the working principle of the engine oil level sensor is quite simple. If the oil level drops below a preset level, the sensor sends a signal to the car's main computer, which sends a message to the dashboard.

Most oil level sensors work by electrical resistance. The smaller the part of the sensor covered by oil, the greater the change in the resistance value. In contrast, more modern or luxury cars use advanced ultrasonic sensors with a piezoelectric frequency converter that sends pulses into the oil itself to produce echoscopic response signals. This information is then transmitted to the ECU.

What are the symptoms of a faulty oil sensor?

In modern cars, there are three ways to identify oil level sensor faults.

Different gauge readings

When a low engine oil level message appears on the dashboard, immediately use a conventional engine oil level dipstick. Perform two or three oil level checks to make sure the oil level is correct. If the oil level readings do not match, you may conclude that the oil level sensor is defective.

The oil level warning light is constantly on or off

If the engine oil level is actually lower than it should be, then the warning light should be on continuously. If the warning light on the dashboard comes on, goes off again or stays on for a short period of time, this indicates a fault with the oil level sensor.

Check Engine symbol illuminates

In some vehicles, the diagnostic systems in the vehicle will indicate a faulty engine oil sensor not by a separate message but by a general message, which will cause the Check Engine symbol on the dashboard to light up.

Is it safe to drive with low oil levels?

In short, no. For the oil to do its job, the oil level must be at the right level.

How do I change the engine oil pressure sensor?

Normally, replacing the engine oil pressure sensor won't take too much of your time. In most cars, the oil pressure sensor can be changed in about 10-15 minutes.

However, to do this, you will need to drain the oil from the engine first. Then carefully inspect the engine crankcase and locate the connector coming out of it. Unscrew the necessary screws and simply remove the sensor there.

Unfortunately, on some cars the oil pressure sensor is integrated in the engine crankcase itself, so you will need to remove the oil pan to replace it.