Oil pressure sensor

Oil pressure sensors - OPS

The oil pressure sensor is a fundamental part of the internal combustion engine. It is also sometimes called 'oil pressure transmission unit' or 'oil pressure switch (OPS)'. Its purpose is to monitor the oil pressure in the engine. Oil pressure must be maintained at certain levels to ensure that oil reaches all vital parts of the engine.
What does the oil pressure sensor do?
An oil pressure sensor is a simple device that activates a warning light on the dashboard when the engine oil pressure is not within the set levels. It is a very simple device consisting of a spring-loaded switch and a diaphragm. The diaphragm receives oil and is designed to stay open at a set pressure level.
The pressure pushes the diaphragm into the switch and keeps the warning lamp off. If the pressure level is not reached, then the switch will trigger the dash light. In general, the oil pressure sensor is there to recognize low oil pressure, not high oil pressure.
Low oil pressure can cause serious engine damage and may be the result of a clogged oil filter, faulty oil pump or other reasons. The purpose of the oil sensor is to give enough warning to stop the engine before any of these things cause real damage.
How does the oil pressure sensor work?
Most oil pressure sensors are of the simple switch type described in the previous section. The switch opens the electrical circuit if there is a minimum level of oil pressure. Another version is an actual sensor that measures oil pressure.
For the switch version, you may see the warning light on the dashboard when the ignition is on, but not when the engine is off. This is because the switch needs oil pressure to open. When the engine is started, the oil pump starts to build up pressure. As soon as the minimum pressure is reached, the switch opens and the warning lamp will go out.
Where is the oil pressure sensor?
The oil pressure switch or sensor is usually located in the cylinder block, next to the oil filter or oil filter housing. Older vehicles usually have the OPS connected directly to the oil pressure gauge.
On newer vehicles, OPS works a little differently. Usually the sensor is connected to the electronic control module. It measures the actual oil pressure and sends the information to the engine computer. Oil pressure sensors are designed to last the lifetime of the vehicle, but there is always the possibility that they could fail.

Oil pressure sensor problems
OPS can develop certain problems. A common problem is when oil starts to leak. It could be leaking from the actual sensor or from the tread. The tread can be resealed, but if the actual sensor is leaking, then it will need to be replaced.
Another problem is when the OPS clogs or has some other internal malfunction that makes it unable to read oil pressure correctly. This can lead to the on-board gauge lighting up even if the oil pressure is fine.
How to test the oil pressure sensor?
The test procedure is different depending on the type of OPS the engine has. The first step is to check the level and quality of the engine oil. Low oil pressure lights often come on due to inadequate oil level.
The light may also come on if the oil is extremely old and of degraded quality. Otherwise the sensor cables should be tested and the actual oil pressure in the engine should be tested. To measure oil pressure, you will need an oil pressure gauge that uses a special adapter to plug in where the original OPS would plug in.
If the oil pressure is low with the engine running, then it is a real engine problem. If the pressure is within the correct range and the sensor wiring is ok, then the problem is the real sensor.