The Air Filter Restriction Sensor (AFRS) is available only with the Maintenance Alert System (Release 27.0 or later software). The AFRS has two trip points, one at 18 in. of water and the second at 25 in. of water. See Figure 3-29. An air filter will be considered to be restricted if the AFRS reads 18 in. of water and the engine is below 1500 rpm or the AFRS reads 25 in. of water at any engine speed. The air filter restriction logic will look for two restrictions that have occurred at least 24 engine hours apart, but no more than 72 hours apart.
The AFRS is mounted downstream of the air filter and upstream of the turbocharger. The AFRS must be in a straight section of pipe or where the OEM mechanical unit is normally mounted. This sensor must be enabled with Vehicle Electronic Programming System, (VEPS, release 24 software or later) or the DDEC Reprogramming System (DRS). A pigtail on the DDC installed engine sensor harness will be used to wire the sensor. See Figure 3-30.