Car Mechanics (UK)
DIESEL PRESSURE DIFFERENTIAL SENSORS
Hollow tubes are fitted to either end of the DPF to transmit exhaust gas pressure to an electrical pressure sensor, which tends to be mounted on the bulkhead. Based on the two pressure inputs, a degree of DPF blockage is calculated and communicated back to the engine ECU. These sensors can develop faults and it is not unknown for even new replacements not to work properly, or have incompatible software. So, prior to condemning the DPF, check your live diagnostics for pressure readings to see if they are realistic and test the sensor. This is explained in more detail within the February 2018 issue of CM.
Should you need to remove the DPF, these pressure tubes, as well as a temperature sensor, will need to be removed. Consider also that some DPF cleaning products can be poured directly into the DPF through the pressure pipes.