Skip to Content

ISX Oil Pressure Sensor Location: How To Find It? [Quickly & Easily]

Do you need to replace the oil pressure sensor on your Cummins ISX Engine, and do you want to know how to find the old oil pressure sensor? You’ve come to the right place, for we have researched this question and have the answer for you. Let's dive in!

The oil filter is on the driver’s side of the engine, behind the fuel filter. Locate the fuel filter on the driver’s side of the engine, then follow the wire harness behind it.

Let’s talk more about the oil pressure sensor and how to replace the one in your ISX in the succeeding sections. With that said, let's get right into it.

Before you continue reading, let us say we hope you find the links here useful. If you purchase something through a link on this page, we may get a commission, so thank you!

Cummins Incorporated Explained

Founded in 1919, Cummins Incorporated is an American multinational corporation that manufactures and distributes filtration and power generation products and engines.

Cummins is an engine designer and developer for Dodge and Ram.

Cummins became one of the defendants in a class-action suit in 2008. This is about the Chrysler Dodge Ram trucks of year models 1998 to 2001 of the 2500 or 3500.

The Cummins ISB 5.9L diesel engine on these trucks has a defect on the engine block. The block allegedly cracks and causes the coolant to leak.

The ISB 5.9L uses a Bosch VP44 rotary injection pump.

What Is A Straight-Six Engine?

A straight-six or inline-six engine uses an inline design instead of a V-format.

An inline design means that the engine cylinders are all in a straight line.

This type of engine is cheaper to produce because you only need one cylinder head for the engine instead of two heads and valvetrains like in a V6 configuration. Fewer parts in the engine mean fewer parts that could go wrong.

Since the engine has only one cylinder head, the route of the coolant and oil inside the engine is simpler. This makes the cooling and lubricating system more efficient.

The simple design of an inline-six engine makes it easier to service and maintain. You can access all the spark plugs in a single location and replace them if needed. The same easy access applies to other components of the engine.

Thus, an inline-six engine is ideal for vehicles that travel long distances because it is simpler to work on if it breaks down in the middle of the journey.

The Cummins ISX engine adapts the inline-six engine design.

Straight-six engine

Engine Balance

The biggest advantage of an inline-six engine is engine balance. A straight-six engine has a regular firing order. Half of the pistons move in tandem with their mirror image.

Thus, pistons one and six will move at the same time. Pistons two and five would follow at 120 degrees, then pistons three and four at 240 degrees. This configuration causes the reciprocating forces from the pistons to balance each other out.

Straight-six engines are known for their smooth revving. This also means that the engine generates less vibration while it runs. There are only two directions that the pistons travel: downward and upward.

However, smooth revs are not the only thing that inline-six engines are famous for.

The configuration of the pistons allows the engine to produce higher torque at higher speeds than a V6 engine. Thus, many offroad vehicles use inline-six engines to take advantage of the extra torque.

This is one of the reasons why manufacturers often equip trucks with inline-six engines instead of V6 engines—because trucks need torque, whatever the speed.

Disadvantages Of A Straight 6 Engine

A straight-six engine is longer than a V6 engine because the cylinders are straight.

This can make it challenging for the oil and water pump to push coolant and oil to the last two cylinders. It would help if you replaced the oil pump and water pumps that are starting to fail because they will have a hard time pushing coolant and oil to the farthest two cylinders.

Another disadvantage of inline-six engines is that they cannot have front-wheel drives. An inline-six engine does not allow an efficient design to mate it with a front-wheel drive.

Volvo attempted to build inline six vehicles with front-wheel drive. However, the resulting configuration is inefficient.

Inline six engines produce lower speeds than a V6 engine. The crankshaft is longer in an inline-six engine, and this causes the air to find it challenging to reach the last two cylinders.

The Cummins ISX Engine

Long hauler professional industrial white big rig semi truck tractor transporting commercial cargo

The ISX is an inline-six diesel engine that came out in 2001. It took over the N14 diesel engine because the EPA’s emissions standards became stricter.

The Cummins ISX immediately became a popular engine you’d commonly see on the road until now, becoming America’s most popular heavy-duty engine. It is the only engine available from each major Class 8 truck manufacturer in the country.

The ISX can produce 430 to 620 horsepower and a peak torque of 2,050 pound-foot. It has a maximum RPM of 1,800 and a dry engine weight of 2,964 pounds.

The ISX uses an IFSM (Integrated Fuel System Module) with a lift pump, gear pump, pressure regulators, and a shutoff valve. It also uses metering and timing actuators to deliver fuel to the injectors.

The 2002 version is the first in the line to include an EGR (exhaust gas recirculation) system that recirculates some of the exhaust gases back into the intake of the engine.

This helps lower the temperatures inside the combustion chamber and limits the amount of NOx byproduct. The 2008 update of the engine—the ISX CM871—features a DPF filter.

DPF or diesel particulate filter traps soot that comes from the combustion of air and fuel. The DPF and the DOC (Diesel Oxidation Catalyst) oxidize the soot into ash.

This process is known as filter regeneration.

Why The Oil Pressure Sensor Fails In An ISX

Oil pressure sensor

The oil pressure sensor for the Cummins ISX engine is an inexpensive part. However, it is known for leaking oil through the base seal of the sensor or electronic connectors.

When the oil pressure sensor fails or leaks, you will need to replace the sensor.

A common symptom is a sudden drop in the oil pressure gauge of the truck. A failing sensor will no longer be able to provide an accurate reading. Therefore, the gauges will no longer provide correct information.

Once you start getting an erratic reading from the oil pressure gauge, check the oil pressure sensor for the presence of oil. Oil in the sensor means that the seals are broken and can no longer handle the oil pressure to provide an accurate reading.

Replacing The Oil Pressure Sensor In Your ISX

  1. Locate the oil sensor behind the fuel filter.
  2. Unplug the ECM.
  3. Use a 90-degree pick to push the connector’s lock and unlock the wire harness. Once you unlock the wire harness, pull it off. Check the connector. The presence of oil on the connectors means that the oil pressure sensor needs a replacement.
  4. Use a socket to loosen the old oil pressure sensor, then remove it.
  5. Pull the old oil pressure sensor.
  6. Insert the new oil pressure sensor.
  7. Torque the new oil pressure sensor.

CENTAURUS Oil Pressure Sensor is available on Amazon.

Channellock HP-4A 4-Piece Hook and Pick Set are on Amazon.

Camshaft Timing Wedge Issue

engine timing shaft for motorcycles

A common problem in ISX engines will seem like it is an issue with the oil pressure sensor. This problem usually happens after an overhaul, a camshaft repair, or any repair that can affect the timing.

Timing the ISX is done through a timing wedge that can wear out. A worn timing wedge will cause changes in the timing of the camshaft.

When the timing is off, there is a possibility that the fuel injection will become off too. Fuel injection that is out of time leads to the production of soot inside the engine. Soot inside the engine can mix with the engine oil and contaminate it.

Unfortunately, soot in the engine oil will lead to blockage in the oil filter. This blockage will eventually lead to a drop in the oil pressure.

At first glance, this can appear to be a problem with the oil pressure sensor. The sudden drop in oil pressure on the gauges will initially point to a sensor issue.

To make it worse, there could be a real problem with the oil pressure sensor once you check it since that is also a common issue.

However, replacing the oil pressure sensor will not resolve the drop in oil pressure.

Signs To Look Out For

Big rig long haul bonnet fresh gray diesel semi truck with chrome grille pulls dry van semi trailer, ISX Oil Pressure Sensor Location: How To Find It? [Quickly & Easily]

A drop in the oil pressure is the most common symptom. This will lead to power loss and a burning smell from the engine.

Another symptom is an increase in engine noise with an increase in the engine temperature. In some models, the oil warning light will turn on to notify you about the drop in the engine oil pressure.

Once you replace the oil pressure sensor and the problem is still present, replace the oil filter. Check the oil filter for soot. The presence of soot means that you have this issue.

After you replace the oil filter, you will need to bring your engine in to correct the timing. This will prevent the problem from happening again.

This ISX Cam Timing Tool Kit is available on Amazon.

To Finish Up

Big rig long haul bonnet fresh gray diesel semi truck with chrome grille pulls dry van semi trailer

Finding the oil pressure sensor is easy. However, replacing it can be a challenge without the right tools. Therefore, you want to ensure you gather everything you need and follow our above steps: good luck!

Made it to the end? Check out these helpful related articles:

How To Bypass DPF Pressure Sensor [Is It Possible]?

Can You Unplug Oil Pressure Sensor [Can I Drive With It Unplugged]?