System and method of isolating component failures in an exhaust aftertreatment system

A system, comprising:

• an exhaust aftertreatment system including a selective catalytic reduction (SCR) system, a diesel oxidation catalyst (DOC), and a catalyzed diesel particulate filter (DPF);
• and
• a controller communicably coupled to the exhaust aftertreatment system, the controller structured to:
• determine that the exhaust aftertreatment system is purged of a reductant deposit;
• determine a first SCR efficiency;
• reduce a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determine a second SCR efficiency;
• and
• determine a state of at least one of the DOC, DPF, and SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein the controller is structured to determine that only the DOC and DPF are in a degraded state based on the first SCR efficiency being at or above the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.

A system, comprising:

• an exhaust aftertreatment system including a selective catalytic reduction (SCR) system, a diesel oxidation catalyst (DOC), and a catalyzed diesel particulate filter (DPF);
• and
• a controller communicably coupled to the exhaust aftertreatment system, the controller structured to:
• determine that the exhaust aftertreatment system is purged of a reductant deposit;
• determine a first SCR efficiency;
• reduce a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determine a second SCR efficiency;
• and
• determine a state of at least one of the DOC, DPF, and SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein the controller is structured to determine that the DOC, DPF, and SCR are all in a degraded state based on the first SCR efficiency being below the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.

A method, comprising:

• purging an exhaust aftertreatment system of a reductant deposit;
• determining that the exhaust aftertreatment system is purged of the reductant deposit;
• determining a first SCR efficiency;
• reducing a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determining a second SCR efficiency;
• and
• determining a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein determining the state includes determining that only the DOC and DPF are in a degraded state based on the first SCR efficiency being at or above the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.

A method, comprising:

• purging an exhaust aftertreatment system of a reductant deposit;
• determining that the exhaust aftertreatment system is purged of the reductant deposit;
• determining a first SCR efficiency;
• reducing a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determining a second SCR efficiency;
• and
• determining a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein determining the state includes determining that the SCR, DOC, and DPF are all in a healthy state based on the first and second SCR efficiencies being at or above the high SCR efficiency threshold.

A method, comprising:

• purging an exhaust aftertreatment system of a reductant deposit;
• determining that the exhaust aftertreatment system is purged of the reductant deposit;
• determining a first SCR efficiency;
• reducing a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determining a second SCR efficiency;
• and
• determining a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein determining the state includes determining that only the DOC is in a healthy state based on the first SCR efficiency being below the high SCR efficiency threshold and the second SCR efficiency being within a marginal SCR efficiency range, wherein the marginal efficiency range is above the low SCR efficiency threshold.

A method, comprising:

• purging an exhaust aftertreatment system of a reductant deposit;
• determining that the exhaust aftertreatment system is purged of the reductant deposit;
• determining a first SCR efficiency;
• reducing a temperature of exhaust gas flowing through the exhaust aftertreatment system;
• determining a second SCR efficiency;
• and
• determining a state of at least one of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a SCR system based on the first and second SCR efficiencies relative to a low SCR efficiency threshold and a high SCR efficiency threshold, wherein determining the state includes determining that the DOC, DPF, and SCR are all in a degraded state based on the first SCR efficiency being below the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.

An apparatus, comprising:

• an exhaust aftertreatment system including, a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) system;
• a controller communicably coupled to the exhaust aftertreatment system and including:
• a dosing circuit configured to suspend dosing in the exhaust aftertreatment system;
• and
• a system diagnostic circuit configured to determine an efficiency of the SCR system over a range of SCR inlet temperatures and reduce a temperature of an exhaust gas flowing through the exhaust aftertreatment system, wherein the system diagnostic circuit is further configured to determine a state of at least one of the diesel oxidation catalyst (DOC), the diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR inlet temperature range and the SCR efficiency at a relatively lower SCR inlet temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold;
• wherein the system diagnostic circuit is configured to determine that the SCR, DOC, and DPF are all in a healthy state based on the first and second SCR efficiencies being at or above the high SCR efficiency threshold.

An apparatus, comprising:

• an exhaust aftertreatment system including, a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) system;
• a controller communicably coupled to the exhaust aftertreatment system and including:
• a dosing circuit configured to suspend dosing in the exhaust aftertreatment system;
• and
• a system diagnostic circuit configured to determine an efficiency of the SCR system over a range of SCR inlet temperatures and reduce a temperature of an exhaust gas flowing through the exhaust aftertreatment system, wherein the system diagnostic circuit is further configured to determine a state of at least one of the diesel oxidation catalyst (DOC), the diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR inlet temperature range and the SCR efficiency at a relatively lower SCR inlet temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold;
• wherein the system diagnostic circuit is configured to determine that only the DOC and DPF are in a degraded state based on the first SCR efficiency being at or above the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.

An apparatus, comprising:

• an exhaust aftertreatment system including, a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic reduction (SCR) system;
• a controller communicably coupled to the exhaust aftertreatment system and including:
• a dosing circuit configured to suspend dosing in the exhaust aftertreatment system;
• and
• a system diagnostic circuit configured to determine an efficiency of the SCR system over a range of SCR inlet temperatures and reduce a temperature of an exhaust gas flowing through the exhaust aftertreatment system, wherein the system diagnostic circuit is further configured to determine a state of at least one of the diesel oxidation catalyst (DOC), the diesel particulate filter (DPF), and the SCR system based on the SCR efficiency at an elevated SCR inlet temperature range and the SCR efficiency at a relatively lower SCR inlet temperature range relative to a high SCR efficiency threshold and a low SCR efficiency threshold;
• wherein the system diagnostic circuit is configured to determine that the DOC, DPF, and SCR are all in a degraded state based on the first SCR efficiency being below the high SCR efficiency threshold and the second SCR efficiency being at or below the low SCR efficiency threshold.