Gasoline particulate filter diagnostics

A system for an engine, comprising:

• a particulate filter coupled in an exhaust passage;
• a differential pressure sensor;
• an upstream hose coupling the differential pressure sensor to the exhaust passage upstream of the particulate filter;
• a downstream hose coupling the differential pressure sensor to the exhaust passage downstream of the particulate filter;
• an exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter;
• and
• a controller storing instructions executable to:
• selectively adjust a position of the exhaust tuning valve based on an operator-selected noise mode;
• and
• responsive to a command to perform a diagnosis of the downstream hose, adjust the position of the exhaust tuning valve to a fully open position and to a fully closed position, and indicate degradation of the downstream hose based on output from the differential pressure sensor while the exhaust tuning valve is at the fully open position and while the exhaust tuning valve is at the fully closed position.

A method of operating a vehicle having an engine and a particulate filter coupled in an engine exhaust system, comprising:

• responsive to a command to perform a diagnosis of a downstream hose coupling a differential pressure sensor to an exhaust passage downstream of a particulate filter in the exhaust system, indicating degradation of the downstream hose based on output from the differential pressure sensor while an exhaust tuning valve is fully open and while the exhaust tuning valve is fully closed, the exhaust tuning valve coupled across a muffler positioned in the exhaust passage downstream of the particulate filter;
• when the downstream hose is not indicated as degraded, and responsive to particulate filter diagnosis conditions being met, performing a particulate filter diagnosis routine to indicate degradation of the particulate filter based on the output from the differential pressure sensor, independent of exhaust tuning valve position;
• and
• when the downstream hose is indicated as degraded, and responsive to particulate filter diagnosis conditions being met, delaying performance of the particulate filter diagnosis routine until the downstream hose is no longer indicated as degraded.