Patent ID: 8457927
Filing Date: 2013-06-04
Classification: F01N,F02D,Y02A,Y02T

Abstract:
1. A method for diagnosing the functional reliability of a lambda probe which is located in an exhaust gas line in the outflow direction of an exhaust gas emerging from an internal combustion engine downstream of at least one section of a catalytic converter with oxygen storage capacity, the method comprising recording, via a processor, at least one signal from the lambda probe during a time interval, wherein the time interval depends on an instant of a change from one selected from the group consisting of lean to rich exhaust gas and rich to lean exhaust gas such that directly as a consequence of the change for a fully functional lambda probe the oxygen charging of the catalytic converter exceeds a predetermined lower boundary value or falls below a predetermined upper boundary value, wherein the predetermined lower boundary value is oxygen charging of between 5% and 15% and the predetermined upper boundary value is oxygen charging of between 85% and 95%; diagnosing the functionality of the lambda probe, via a processor, by comparing a numerical derivative value, which includes the time derivative of a voltage signal of the lambda probe at least one instant from the time interval to a threshold value according to a predetermined criterion.