PACCAR MX-13 oil pressure sensor location
Direct answer and scope
On the PACCAR MX-13, the engine oil pressure sensor is normally mounted on the left-hand side of the engine block, toward the rear and below the intake manifold area. The exact position can shift slightly by model year and emissions calibration, but the sensor is consistently placed in the main oil gallery so it reads pressurized engine oil rather than a low-pressure return path.
The location is broadly similar across EPA 2010, EPA 2013, EPA 2017 and later greenhouse-gas calibrations used in Peterbilt and Kenworth trucks. The most material difference is access: chassis packaging, frame rail proximity and aftertreatment hardware can change how visible or reachable the sensor is even when the engine block position has not moved.
How to recognize it
The oil pressure sensor is a small cylindrical switch-style sender with an electrical connector, usually secured into a threaded port with a wrench hex at its base. Depending on the supplier, the connector may be a two-pin or three-pin sealed automotive-style plug. Do not confuse it with the coolant temperature sensor, which is also threaded into the block but is typically located in a coolant passage rather than the oil gallery and often has a different connector key.
A useful identification cue is the wire path. The oil pressure sensor pigtail tends to route along the left side of the engine and join the main chassis or engine harness near the ECM area. If the connector is oily or darkened with engine oil residue, that is another indicator you are looking at the oil pressure sender rather than a coolant or fuel component.
Practical notes for location work
The rearward placement means you may need to work from above the left frame rail or through a wheel-well opening, depending on cab configuration. On trucks with a dipstick tube, the sensor is generally behind or slightly inboard of the tube, not directly beside it. The main oil gallery provides a stable pressure signal, so the sensor is intentionally placed where it is less affected by localized turbulence near the oil pump inlet.
If the engine is equipped with an oil pressure warning system tied to a gauge, the sensor may be a dual-function sender that reports both pressure and switch state. A replacement sensor must match the vehicle calibration because the ECM interprets voltage from the sender. A wrong-range part can trigger false low-pressure warnings even when mechanical oil pressure is normal.
What is not covered here
This guide does not include torque specifications, diagnostic trouble-code tables or removal steps. Those values vary by service information and should be confirmed for the specific engine serial number and emissions level before disassembly. Material uncertainty remains for unusual vocational chassis where a body builder may have added shielding around the sensor area.