METHOD AND DEVICE FOR THE ON-BOARD DIAGNOSIS OF AN NOX SENSOR

摘要

The invention relates to a method for the on-board diagnosis of an NOX sensor which is preferably situated in an exhaust gas system of an engine, and which has a regulating device for regulating an oxygen partial pressure and an NOX measuring device for providing an NOX signal characterising the NOX concentration in the exhaust gas, in order to measure the NOX concentration of an exhaust gas. According to the invention, a lambda signal characterising the lambda value of the exhaust gas, preferably a broadband lambda signal or a lambda step signal, is determined. The determined values of the lambda signal are compared with plausible lambda values for the exhaust for predetermined operating parameters and an NOX sensor diagnosis signal is formed according to the result of the comparison. Alternatively, the values of the NOX signal can be compared with plausible values for the NOX concentration for predetermined operating parameters and an NOX sensor diagnosis signal formed according to the result of the comparison. The inventive device for on-board diagnosis is used to carry out the inventive method.