Differential pressure: why two points are needed

Useful to know

The differential pressure sensor compares the pressure in two places in the flow. Bosch describes its use to monitor a particulate filter and to control low-pressure exhaust gas recirculation. In a filter, information assists in the assessment of regeneration accumulation and management. [1]

Imagine a filter between two points of measurement. The quantity sought is the difference through it, not just the pressure in any location from the exhaust system. This explains why the two relationships are part of the meaning of measurement.

A high number without working conditions is not enough for a conclusion. The flow of gases, the instantaneous mode and the particular system matter. The text explains the principle without setting a universal threshold for all cars or guidelines for forced regeneration.