INTAKE OXYGEN SENSOR RATIONALITY DIAGNOSTICS

摘要

Rationality diagnostic techniques for an intake oxygen sensor are utilized to detect sensor malfunction. A non-intrusive diagnostic technique includes passively detecting when an exhaust gas recirculation (EGR) valve position crosses low/high position thresholds, whereas an intrusive diagnostic technique includes actively commanding the EGR valve to predetermined low/high positions. During a period after the EGR valve position reaches/crosses at least one of the low/high positions/position thresholds, respectively, maximum and minimum intake oxygen concentration is monitored. When the EGR valve position has crossed both the low/high positions/position thresholds and a difference between the maximum and minimum oxygen concentrations is less than a respective difference threshold, a malfunction of the intake oxygen sensor is detected. A malfunction indicator lamp (MIL) could be set to indicate the malfunction. The intrusive technique is additionally or alternatively implemented, such as part of a verification or backup to the non-intrusive technique.

主权项

1. A diagnostic system comprising:
an intake oxygen sensor configured to measure an oxygen concentration in an induction system of an engine at a point downstream from an exhaust gas recirculation (EGR) port and upstream from a throttle valve; an EGR valve position sensor configured to measure a position of an EGR valve; and a controller configured to perform a non-intrusive rationality diagnostic for the intake oxygen sensor, the non-intrusive rationality diagnostic comprising:
detecting when the EGR valve position measured by the EGR valve position sensor has crossed low and high position thresholds;during a period after detecting that the EGR valve position has crossed one of the low and high position thresholds, determining maximum and minimum oxygen concentration measured by the intake oxygen sensor; andin response to the detecting that the EGR valve position has crossed both the low and high position thresholds, detecting a malfunction of the intake oxygen sensor based on a comparison between (i) a difference between the maximum and minimum oxygen concentrations and (ii) a difference threshold indicative of an acceptable range of measurement by the intake oxygen sensor.