The oil pressure switch is also known as the oil pressure sensor. It will cause the low oil pressure light to go on if it detects a lack of oil, but an oil pressure switch isn’t infallible. It can become faulty and when this happens, you’ll need to replace it. This isn't a hard task and it can be done easily when you're performing a routine oil change.
Step 1 - Locate the Switch
The placement of the oil pressure switch will vary with car make. As a general rule, however, you’ll find the switch close to the oil filter or just under it. If you’re not certain, the best thing to do is consult the service manual for your vehicle.
Step 2 - Drain the Oil
Since it can be difficult to obtain good access to the oil pressure switch when the oil filter is on, changing the oil pressure switch as part of a service is suggested. To do this, place a large basin under the oil pan and open the drain plug with a wrench. Then, using an oil filter wrench, loosen the oil filter before removing it by hand. You’ll now be able to get to the oil pressure switch.
Step 3 - Remove the Switch
You’ll see that a connect cable goes to the oil pressure switch that you need to unplug. There will be a rubber boot covering and protecting the switch to keep dirt away. You’ll need to carefully peel it back from the switch and then push down on a tab. Doing this will let you unlock the connector to the oil pressure switch, and then you’ll be able to remove the boot.
While it’s off, take a rag and clean the contacts on the connector to help eliminate later problems. Then, fit your wrench over the oil pressure switch and add the extender handle. Loosen the switch before you finish unscrewing and removing it by hand.
Step 4 - Replace with a New Switch
If any oil spills when you remove the oil pressure switch, wipe it up with a rag before you screw the new switch in with your hand. Tighten it all the way down with your socket wrench. Then, snap the connector on to the new switch and roll down the boot so the oil pressure switch is fully protected. Clip the cable back onto the switch.
Step 5 - Add New Filter and Oil
Dip your finger in the old oil in your basin and run over the rubber gasket on the new filter before you screw it onto the engine. Use the oil filter wrench to secure it firmly. Then, close the drain plug on the oil pan and refill the engine with the correct amount of new oil; your service manual will tell you how much to put in.
Finish by putting the oil cap back on. Check your work before you clean up by switching on the engine and checking that the oil pressure switch is working correctly. It should not come on at all if the work carried out is satisfactory. Finally, dispose of the old oil and filter responsibly.