Method to detect and mitigate unsolicited exotherms in a diesel aftertreatment system

A method for diagnosing undesired exotherms in an exhaust aftertreatment system, the aftertreatment system having at least a first region including particulate filter trapping and regeneration and a second region without particulate filter trapping, the system coupled to an engine, the method comprising:

• during regeneration of the first region:
• adjusting an engine operating condition in response to an oxygen concentration downstream of the aftertreatment system to maintain a desired oxygen concentration downstream of the aftertreatment system;
• and
• indicating an undesired exotherm in the second region based on a difference between an expected oxygen concentration and the oxygen concentration downstream of said exhaust aftertreatment system;
• and
• initiating mitigating actions in response to said indicating of the undesired exotherm.

A method for diagnosing undesired exotherms in an exhaust aftertreatment system coupled to a combustion engine, the method comprising:

• determining an expected temperature at a location downstream of a first catalyst, based on an oxygen concentration measured at a sensor located downstream of the first catalyst, a measured temperature upstream of the first catalyst and downstream of a second catalyst, and the exhaust flow;
• determining a threshold for the difference between the expected temperature and the measured temperature based on engine and exhaust conditions;
• indicating an undesired exotherm if the difference between the expected temperature and the measured temperature is greater than the threshold;
• and
• initiating mitigating actions in response to said indicating of the undesired exotherm.