An engine system includes an internal combustion engine, a main exhaust aftertreatment system with a main catalytic converter, and a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter. An emissions control system includes a controller in signal communication with an oxygen sensor disposed downstream of the bypass catalytic converter. The emissions control system performs a diagnostic of the bypass catalytic converter, by the controller, including (i) monitoring signals from the downstream oxygen sensor for a predetermined time period during an engine cold start condition, (ii) determining a curve plotting oxygen content at the downstream oxygen sensor over the predetermined time period, based on the signals from the downstream oxygen sensor, (iii) calculating an accumulated area under the curve over the predetermined time period, and (iv) comparing the calculated accumulated area to a predetermined threshold to determine if the bypass catalytic converter has failed.

A method for protecting an exhaust aftertreatment system of an internal combustion engine from deterioration by selectively diverting exhaust gasses from the engine away from a component of the exhaust aftertreatment system includes assessing a status of an operating condition associated with a physical condition of the component of the internal combustion engine. The status of the operating condition is compared with a threshold value that corresponds with deterioration of the physical condition of the component. A valve upstream of the component is moved to a first position to open a bypass fluid path directing exhaust gasses around the component when the status of the operating condition meets the threshold value to reduce deterioration of the component. The valve is moved to a second position to close the bypass fluid path thereby directing exhaust gasses to the component when the status of the operating condition does not meet the threshold.

An engine system includes an internal combustion engine, a main exhaust aftertreatment system with a main catalytic converter, and a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter. An emissions control system includes a controller in signal communication with an oxygen sensor disposed downstream of the bypass catalytic converter. The emissions control system performs a diagnostic of the bypass catalytic converter, by the controller, including (i) monitoring signals from the downstream oxygen sensor for a predetermined time period during an engine cold start condition, (ii) determining a curve plotting oxygen content at the downstream oxygen sensor over the predetermined time period, based on the signals from the downstream oxygen sensor, (iii) determining a number of times the curve crosses a predetermined setpoint over the predetermined time period, and (iv) comparing the number to a predetermined threshold to determine if the bypass catalytic converter has failed.

An engine system includes an internal combustion engine, a main exhaust aftertreatment system with a main catalytic converter, and a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter. An emissions control system includes a controller in signal communication with an oxygen sensor disposed downstream of the bypass catalytic converter. The emissions control system performs a diagnostic of the bypass catalytic converter, by the controller, including (i) monitoring signals from the downstream oxygen sensor for a predetermined time period during an engine cold start condition, (ii) determining a curve plotting oxygen content at the downstream oxygen sensor over the predetermined time period, based on the signals from the downstream oxygen sensor, (iii) determining a number of times the curve crosses a predetermined setpoint over the predetermined time period, and (iv) comparing the number to a predetermined threshold to determine if the bypass catalytic converter has failed.

A method for protecting an exhaust aftertreatment system of an internal combustion engine from deterioration by selectively diverting exhaust gasses from the engine away from a component of the exhaust aftertreatment system includes assessing a status of an operating condition associated with a physical condition of the component of the internal combustion engine. The status of the operating condition is compared with a threshold value that corresponds with deterioration of the physical condition of the component. A valve upstream of the component is moved to a first position to open a bypass fluid path directing exhaust gasses around the component when the status of the operating condition meets the threshold value to reduce deterioration of the component. The valve is moved to a second position to close the bypass fluid path thereby directing exhaust gasses to the component when the status of the operating condition does not meet the threshold.

A method of controlling an exhaust gas aftertreatment system includes receiving a plurality of emissions values from a plurality of sensors disposed in an aftertreatment system, determining a real-time conversion efficiency for one or more legs of the aftertreatment system based on the emissions values, determining a real-time conversion metric for the aftertreatment system based on the real-time conversion efficiency for the one or more legs, comparing the real-time conversion metric to an upper threshold value, and initiating a cleaning operation to clean the aftertreatment system based on a determination that the real-time conversion metric satisfies the upper threshold value.

A method of controlling an exhaust gas aftertreatment system includes receiving a plurality of emissions values from a plurality of sensors disposed in an aftertreatment system, determining a real-time conversion efficiency for one or more legs of the aftertreatment system based on the emissions values, determining a real-time conversion metric for the aftertreatment system based on the real-time conversion efficiency for the one or more legs, comparing the real-time conversion metric to an upper threshold value, and initiating a cleaning operation to clean the aftertreatment system based on a determination that the real-time conversion metric satisfies the upper threshold value.

An aftertreatment system includes: a first exhaust gas path comprising a heater; a second exhaust gas path comprising a first decomposition chamber configured to receive reductant and a first selective catalytic reduction catalyst downstream of the first decomposition chamber; a combined exhaust gas path downstream of the first exhaust gas path and the second exhaust gas path, the combined exhaust gas path configured to receive exhaust gas from both the first exhaust gas path and the second exhaust gas path; a selector valve configured to divert the exhaust gas between the first exhaust gas path and the second exhaust gas path based on a temperature of the exhaust gas; and a controller programmed to control the selector valve.