This paper presents an innovative approach for measuring particulate matter deposition (soot load) in a diesel particulate filter (DPF) using electrical capacitance imaging. Emission regulations on diesel engines for gaseous as well as particulate matter (soot) emissions are getting stringent every few years by the environment regulatory agencies. Modern diesel engines are equipped with DPFs, as well as on-board technologies to evaluate the status of DPF, because complete knowledge of DPF soot load is very critical for robust and efficient operation of the engine exhaust after treatment system. In course of time, soot will be deposited inside the DPF which will clog the filter and generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot build-up, regeneration (active or passive) of the DPF must be done as an engine exhaust after treatment process periodically. Since the regeneration process consumes fuel, a robust and efficient operation based on accurate knowledge of the soot load becomes essential in order to keep the fuel consumption at a minimum. In this paper, we propose a novel sensing method for a DPF that can measure in situ soot load using electrical capacitance imaging. Experimental results show that the proposed method offers an effective way to measure the soot load in DPF. The proposed method is expected to have a profound impact in improving overall DPF filtering efficiency and durability of a DPF through appropriate closed-loop regeneration operation.