Particulate filter diagnostics

A method for determining whether a particulate filter is operating properly, the method comprising:

• determining whether a particulate sensor particulate stability condition for a particulate sensor is present;
• determining a particulate sensor input value, compensating the particulate sensor input value, filtering the compensated particulate sensor input value, and determining a soot accumulation value in response to the filtered compensated particulate sensor input value;
• determining whether a set of diagnostic enable conditions are active;
• in response to the particulate sensor particulate stability condition, the active diagnostic enable conditions, and the soot accumulation value, determining a state of the particulate filter;
• and
• providing the state of the particulate filter to an output device.

An apparatus, comprising:

• a particulate stability module structured to interpret a particulate stability condition associated with a particulate sensor downstream of a particulate filter in an exhaust system;
• a particulate sensor processing module structured to interpret a particulate sensor input value from the particulate sensor when the particulate stability condition is present, the particulate sensor processing module being further structured to interpret a particulate sensor temperature, to compensate the particulate sensor input value in response to the particulate sensor temperature, and to filter the compensated particulate sensor input value;
• a particulate determination module structured to determine a soot accumulation value in response to the filtered compensated particulate sensor input value;
• a diagnostic screening module structured to interpret a diagnostic enable condition;
• and
• a particulate sensor diagnostic module structured to determine a state of the particulate filter in response to the diagnostic enable condition and the soot accumulation value, and to provide the state of the particulate filter to an output device.

A system, comprising:

• an internal combustion engine producing an exhaust stream;
• a particulate filtering device fluidly coupled to the engine with the exhaust stream passing therethrough;
• a particulate sensor operatively coupled to the exhaust stream at a position downstream of the particulate filtering device;
• a temperature sensor operatively coupled to the exhaust stream;
• a controller connected to the particulate sensor and the temperature sensor, the controller comprising:
• a particulate stability module structured to interpret a particulate stability condition associated with the exhaust stream at the particulate sensor;
• a particulate sensor processing module structured to interpret a particulate sensor input value from the particulate sensor in response to the particulate stability condition being present, the particulate sensor processing module further being structured to interpret a particulate sensor temperature, to compensate the particulate sensor input value in response to the particulate sensor temperature, and to filter the compensated particulate sensor input value;
• a particulate determination module structured to determine a soot accumulation value in response to the filtered compensated particulate sensor input value;
• a diagnostic screening module structured to interpret a diagnostic enable condition;
• and
• a particulate sensor diagnostic module structured to determine a state of the particulate filtering device in response to the diagnostic enable condition and the soot accumulation value, and to provide the state of the particulate filtering device to an output device.