Procedure for the dynamic diagnosis of an exhaust gas probe

Abstract

The invention concerns a procedure for the dynamic diagnosis of an exhaust gas probe disposed in an exhaust gas duct of an internal combustion engine after the emission control system. Provision is made according to the invention for the dynamic diagnosis to be implemented simultaneously with a precipitous change of a Lambda value of the exhaust gas from rich to lean or from lean to rich. During the operating time of an internal combustion engine, step changes in the mixture composition occur for different reasons from rich to lean and from lean to rich. If a dynamic diagnosis of the exhaust gas probe is implemented during such a step change of the mixture composition, provision must not be specially made for such a step change in the diagnosis, which can lead to increased emissions. It is simply to be taken into regard that the mixture composition is suited to the effect that the diffusion barrier is not eliminated due to mixture displacements, which are too large.

1 . A method of diagnosing an exhaust gas probe disposed in an exhaust gas duct of an internal combustion engine, the method comprising dynamically diagnosing the exhaust gas probe simultaneously with a precipitous change of a Lambda value of an exhaust gas from rich to lean or from lean to rich.  
   
   
       2 . A method according to  claim 1 , wherein dynamically diagnosing includes dynamicaly diagnosing simultaneously with a diagnosis of an emission control system and with a precipitous change of the Lambda value of the exhaust gas.  
   
   
       3 . A procedure according to  claim 2 , wherein dynamically diagnosing includes diagnosing after a change of an exhaust gas composition from a Lambda smaller than 1 to a Lambda greater than 1.  
   
   
       4 . A method according to  claim 1 , further comprising determining a step function response from rich to lean based on a rich conditioning of an emission control system and the immediately subsequent precipitous change of an exhaust gas composition from a Lambda smaller than 1 to a Lambda greater than 1.  
   
   
       5 . A method according to  claim 2 , wherein dynamically diagnosing is implemented after a change of an exhaust gas composition from a Lambda greater than 1 to a Lambda smaller than 1.  
   
   
       6 . A method according to  claim 1 , further comprising determining a response diagnosis from lean to rich from a gutting of an emission control system and a lean-rich step change, which occurs in the process.  
   
   
       7 . A method according to  claim 1 , wherein dynamically diagnosing is discontinued, if a diagnosis of an emission control system recognizes it to be in good working order, and the diagnosis of the emission control system is completed ahead of time.