Electric oil pressure gauges are easy for a DIY-mechanic to install, whether replacing a faulty oil pressure gauge, or a custom, aftermarket look is desired. Oil pressure gauges are designed to inform the driver when the oil falls below a safe operating level, or when the oil pressure is too high. Driving a vehicle without an oil pressure gauge can lead to catastrophic engine failure. Most oil pressure gauges come with mounting panels and the necessary installation hardware. The necessary hardware can be purchased from an auto parts dealer, if not included with the oil pressure gauge.
Choose a suitable location to mount the oil pressure gauge; mount the gauge so it is easily viewed while driving. Common mounting locations for aftermarket oil pressure gauges include under the dash, on top of the dash, or set into the dashboard.
Mount the gauge panel to the dash with a screwdriver and screws provided in the kit; set the gauge aside. This makes it easier to connect the wires. If mounting the gauge in the dash, drill a hole in the dash 1/8-inch larger in diameter than the size of the gauge.
Remove the oil drain plug from the oil pan with a wrench and drain the old oil into a oil catch pan. This is an opportune time to change the oil filter as well.
Remove the old oil pressure sending unit with a ratchet and socket; the oil pressure sending unit is shaped like a cylinder and is usually located near the oil filter. Refer to the new oil pressure sending unit in the oil pressure gauge kit to help you identify the part.
Connect the signal wire to the sending unit and run it through a grommet in the firewall in close proximity to the gauge. Run the wire through the gauge panel hole, or the pre-drilled hole in the dashboard, allowing extra wire for easy connecting.
Connect the signal wire to the post on the back of the gauge. The gauge posts are marked for correct wire installation.
Run a power supply wire from a switched 12-volt power supply, such as the cigarette lighter, dome light, radio, or fuel pump, to the power post on the gauge. The power supply must be switched to operate on and off with the ignition.
Run a ground wire from the vehicle chassis to the ground post on the gauge; a poor ground can result in an inoperable gauge or false reading. Use an existing grommet in the firewall, or drill a hole in the body of the vehicle, and route the wire to the chassis or frame.
Mount the gauge into the gauge panel, or the hole in the dash, with the supplied mounting hardware in the kit.
Install the oil pan drain plug and fill the engine with oil.
Start the engine to check the operation of the gauge.