Differential Pressure sensor where is located on International Pro Star 2008

Since that's a DPF sensor, probably on the DPF unit itself.

 

It also can be used on the engine itself to help the ECM control the amount of exhaust gas to recirculate back into the intake from the EGR valve. It is located on the intake side of the engine. At least on my CM871 ISX it is located on the intake manifold near where the EGR mixing pipe connects to the manifold as well. It sits on top of the manifold and has two small tubes that run down to the mixing pipe.

 

Depending on the engine it could be in two places.
The differential pressure sensor is a small black box mounted either in top of the filter unit or on the frame directly above the filter.
Follow the hard metal lines coming from in front and behind the filter module. Those both lead directly to the differential pressure sensor.

 

It's right next to your fuel pump

 

Does your oil pressure drop?

 

Probably same reason as most pro stars Emmision fault

 

Clean the differential pressure sensor tubes and the sensor on the intake