What Is the Oil Pressure Sending Unit?

An oil pressure gauge with the needle sitting at zero.

The oil pressure sending unit controls the oil pressure light or gauge depending on which you car is equipped with. When oil pressure is applied, the switch contacts either shut off the oil light or make the oil pressure gauge active. Basically, the oil pressure sending unit is what sends the oil pressure information to the car’s computer, which then controls the related lights and gauges. It is important for all car owners to know about the different types of sending units that exist, what problems they may have, and any repair information so they can make educated decisions regarding their vehicle whenever there’s an issue.

Knowing the Types

There are three types of oil pressure sending units. The oldest kind is a part in the output side of the oil pump to which a connecting tube is attached. This links up to the gauge on the instrument panel to provide a reading.

Another variety is a screw-in type which has a transducer attached to an electromechanical switch and is connected with a wire to a light on the instrument panel. The sending unit is set to turn the switch on when the oil pressure is below a safe level for use. Since the oil pressure is related to the engine revolutions per minute (RPM), this light will come on at low idle speeds and gradually turn off as the RPM increases.

Finally, there is the third type which is similar to the second type except that it has an electrical voltage output that is directly proportional to the actual oil pressure.

When the Gauge Fluctuates

When it is cold, oil is thicker, and when it is thicker, it needs more pressure to pump the oil. As the oil heats up with use, the pressure will decline to a more normal level.

Troubleshooting the Oil Pressure Sending Unit

Just like any other car part, this piece can malfunction. To troubleshoot the oil pressure sending unit, first unhook the wire going to the unit and ground it with the key on. The gauge should rise to the highest point. If it does, everything is still good. You can also screw the gauge in its place and read the oil pressure.

How Much Does One Cost?

The cost of the oil pressure sending unit depends on the automobile and the model, as well as what is being replaced. Oil pressure sending units can cost anywhere from thirty dollars to over one hundred dollars. You can find them at auto parts stores or online parts stores. Where you decide to shop for your oil pressure sending unit depends on your budget and the urgency of the replacement. Never wait too long if the unit needs replacement, as the delay can compromise your vehicle’s safety.