Methods and systems for an oxygen sensor

摘要

Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected idling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during an idle adaptation relative to a zero point learned during a DFSO adaptation.

主权项

1. An engine method, comprising:
learning a reference point for an intake oxygen sensor at a reference intake pressure during selected engine idling conditions, including correcting an output of the sensor estimated at the reference intake pressure with a correction factor based on ambient humidity; and adjusting engine EGR flow, via an EGR valve, based on an intake oxygen concentration estimated by the sensor relative to the learned reference point and a change in intake pressure from the reference intake pressure.