Offset and slow response diagnostic methods for NOx sensors in vehicle exhaust treatment applications

摘要

A method that includes in-vehicle systems and practices for determining whether a NOx sensor in an exhaust stream is performing properly.

主权项

1. A method of diagnosing vehicle NOx sensor faults, comprising the steps of:
(a) determining that the fuel flow to the vehicle engine is interrupted using an engine control unit (ECU) to monitor a fuel flow sensor; (b) monitoring a NOx sensor at the ECU to determine if the output from the NOx sensor remains above an upper threshold for more than a predetermined amount of time; and (c) if so, then deciding at the ECU that a high-offset error exists for the NOx sensor; (d) otherwise, deciding at the ECU that a low-offset error exists if the output from the NOx sensor falls below a zero or negative threshold for more than a predetermined amount of time.