DPF Differential Pressure Sensor

Two small pipes connect the sensor to the exhaust before and after the DPF. A clean filter causes little pressure drop; a filter loaded with soot or ash causes a much higher one. The control unit uses this reading, together with its own soot model, to decide when to regenerate and to detect a blocked or damaged filter. The sensor is usually mounted on the body or engine and connected to the exhaust before and after the filter by two small pipes or hoses.

A membrane in the sensor bends with the pressure difference, and the sensor converts that into a voltage the control unit reads. As the filter fills with soot, the pressure in front of it rises compared to behind it. The control unit uses this difference, together with a soot model, to decide when regeneration is needed.

A split or blocked sensor pipe, or a faulty sensor, can trigger needless regenerations or hide a blocked filter. Codes in the P2452–P2455 range point to the sensor or its pipes. Cracked, swapped or blocked hoses give false readings that can trigger unnecessary regenerations or warning lights. Checking the pipes is a cheap first step before replacing the sensor or the filter.