A diesel particulate filter (DPF) differential pressure sensor measures exhaust backpressure and signals when the power-train control module (PCM) should begin a regeneration process to clear the filter of diesel particulate matter (DPM), or soot. The DPF differential pressure sensor plays an important role in keeping the DPF functioning properly. A clogged DPF is not only a costly repair, but it can have catastrophic consequences to your diesel engine as well. To understand how the DPF differential pressure sensor works, why it fails, and how to replace it when it does, let’s briefly discuss the DPF.