Abstract: Vehicle oxygen sensor heater diagnostic techniques comprise, upon detection of a set of cold start conditions of the vehicle, measuring an initial resistance of each of a set of two or more oxygen sensor heaters and determining whether any of the measured initial resistances is outside of a nominal resistance range. In response to an outlier oxygen sensor heater being outside of the nominal resistance range, each of the set oxygen sensor heaters is provided with an equal voltage for a period, the resistance of each of the set of oxygen sensor heaters is monitored during the period, and a malfunction of the outlier oxygen sensor heater is detected or matured when a difference between its resistance and the resistances of the other oxygen sensor heaters after the period is greater than a calibrated threshold.

Abstract: Vehicle oxygen sensor heater diagnostic techniques comprise, upon detection of a set of cold start conditions of the vehicle, measuring an initial resistance of each of a set of two or more oxygen sensor heaters and determining whether any of the measured initial resistances is outside of a nominal resistance range. In response to an outlier oxygen sensor heater being outside of the nominal resistance range, each of the set oxygen sensor heaters is provided with an equal voltage for a period, the resistance of each of the set of oxygen sensor heaters is monitored during the period, and a malfunction of the outlier oxygen sensor heater is detected or matured when a difference between its resistance and the resistances of the other oxygen sensor heaters after the period is greater than a calibrated threshold.

Abstract: A lean operation fault detection and isolation (FDI) technique involves receiving, from a manifold absolute pressure (MAP) sensor, a measured MAP, detecting a lean operation fault where an engine is operating with a lean air/fuel ratio, estimating, using an observer, (i) an air/fuel ratio of an exhaust gas produced by the engine and (ii) the MAP, monitoring first and second residual values indicative of differences between (i) the estimated air/fuel ratio of the exhaust gas and a measured air/fuel ratio of the exhaust gas from an exhaust O2 sensor and (ii) the estimated MAP and the measured MAP from the MAP sensor, respectively, and, based on the monitoring of the first and second residual values, determining which of (i) an air intake of the engine, (ii) the exhaust O2 sensor, and (iii) a fuel injector of the engine is malfunctioning and causing the lean operation fault.

Abstract: A lean operation fault detection and isolation (FDI) technique involves receiving, from a manifold absolute pressure (MAP) sensor, a measured MAP, detecting a lean operation fault where an engine is operating with a lean air/fuel ratio, estimating, using an observer, (i) an air/fuel ratio of an exhaust gas produced by the engine and (ii) the MAP, monitoring first and second residual values indicative of differences between (i) the estimated air/fuel ratio of the exhaust gas and a measured air/fuel ratio of the exhaust gas from an exhaust O2 sensor and (ii) the estimated MAP and the measured MAP from the MAP sensor, respectively, and, based on the monitoring of the first and second residual values, determining which of (i) an air intake of the engine, (ii) the exhaust O2 sensor, and (iii) a fuel injector of the engine is malfunctioning and causing the lean operation fault.