Abstract: A method for operating an internal combustion engine (100) and exhaust system therefor includes the step of initiating a regeneration event in a diesel particulate filter (DPF 109) (401). A first oxygen concentration (213) of a gas upstream of the DPF 109, and a second oxygen concentration (215) of the gas downstream of the DPF 109 are sensed (403) to infer a rate of combustion of material in the DPF (405) based on the difference between the first (213) and the second (215) oxygen concentrations. The rate of combustion is compared to a threshold value (409) and the regeneration event in the DPF 109 is terminated (411) if the rate of combustion is above the threshold.

Abstract: An internal combustion engine has cylinders within which combustion occurs and an exhaust system through which products of combustion are exhausted from the cylinders. A temperature sensor and an electric heater are disposed in temperature sensing relation to the exhaust gas flow. A processor develops temperature data obtained from the temperature sensor, and power data representing power required to heat the electric heater to a temperature in excess of temperature of exhaust gas flow past the heater. The processor processes the temperature data, the power data, and data representing mass flow through the engine upstream of the temperature sensor and heater according to an algorithm for yielding data representing difference between mass flow of exhaust gas past the temperature sensor and heater and mass flow upstream of the temperature sensor and heater. The measurement may then be used to measure leakage from the exhaust system by subtracting it from flow measurement in a different location.