On a 2015 JCB 8018 excavator, the low oil pressure sensor is usually mounted on the engine block, typically near the oil filter housing or close to the oil pump assembly. You’ll most likely find it on the side of the engine, threaded into an oil gallery port.
Look for a small, single-wire sensor with a hex base. It should be pretty accessible, especially if you remove the side panel. If it’s tight in there, a deep socket or an offset wrench will help.
Good news is, if you're using the OEM service manual, it should point you to the exact location and give you the torque spec, step-by-step instructions, and clear illustrations if you’re replacing it.