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Reason:
Aftertreatment Diesel Exhaust Fluid Line Heater 2 Circuit – Voltage below normal, or shorted to low source. Low signal voltage detected at the diesel exhaust fluid line heater 2 circuit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel exhaust fluid line heaters are used to defrost and/or prevent freezing of the diesel exhaust fluid lines.

Component Location:
The aftertreatment diesel exhaust fluid line heater 2 is located on the return line between the diesel exhaust fluid dosing unit and diesel exhaust fluid tank.

Conditions for Running the Diagnostics:
This diagnostic runs when the keyswitch is in the ON position and line heating is commanded ON.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the line heater voltage was below a calibratible value and the line heater current was below a calibratable valure.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) The line heater will be disabled.
3) Diesel exhaust fluid injection into the aftertreatment system is disabled.
4) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, and then use INSITE™ electronic service tool to perform the Diesel Exhaust Fluid Doser System Heater Test found under ECM Diagnostic Tests.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
N/A

Possible Causes:
1) A short circuit to ground in the OEM harness
2) A malfunctioning line heater

Reason:
Aftertreatment Diesel Particulate Filter System – Mechanical System Not Responding or Out of Adjustment. The aftertreatment diesel particulate filter has been damaged.

Effect:
Possible reduced engine performance

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter is located in the exhaust system and is installed by the original equipment manufacturer (OEM). Refer to the OEM service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The aftertreatment diesel particulate filter outlet temperature sensor reading was greater than 950°C [1742°F] for 30 seconds, or the difference between the diesel particulate filter intake temperature and the diesel particulate filter outlet temperature was greater than 1050°C [1922° F] for 30 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
2) Active and stationary regeneration of the diesel particulate filter will be disabled.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A malfunctioning engine fuel injector causing unburned diesel fuel to enter the exhaust system
3) A face plugged aftertreatment diesel oxidation catalyst

Reason:
Injector Solenoid Driver Cylinder 6 Circuit – Current Below Normal or Open Circuit. Current detected at injector 6 when voltage is turned OFF.

Effect:
Possible reduced engine performance.

Circuit Description:
The injector solenoid valves control fueling quantity and injection timing. The engine control module (ECM) energizes the solenoid by closing a high-side and a low-side switch. Each injector circuit has a dedicated low side switch that completes the circuit path to ground inside the ECM.

Component Location:
The engine harness connects the ECM to the pass-through connector(s) that are located in the rocker housing. Internal injector harnesses are located under the valve cover and connect the injectors to the engine harness at the pass-through connector(s).

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected a circuit error on an injector(s) circuit. The ECM will disable the injection event for the affected injector(s) circuit if there is excessive current.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) The injector will be disabled for the malfunctioning cylinder.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
If more than one injector fault code is occurring, and the faults occur for injector circuits in the same bank, a short circuit exists. If a fault condition is intermittent, and especially if more than one injector fault code is occurring, look for a wire harness that can short to components inside the rocker housing or a short circuit to ground in the injector solenoid. When looking for short circuits in the injector harnesses, pay particular attention to the wire insulation, making sure there are no shorts to a rocker lever.

An intermittent short can result if the wiring harness insulation rubs through near a rocker lever. An intermittent short can cause a single injector fault code. If the fault(s) occur intermittently, the engine can exhibit a misfire even if the injector circuit fault code does not always register. If a single cylinder exhibits misfires, look for an open circuit problem. If several cylinders on the same bank exhibit misfires, look for a short circuit anywhere in the bank of cylinders.

Possible causes of a single injector fault include:
1) Open circuit in the engine harness(es) or injector solenoid
2) High resistance in a single injector or injector solenoid
3) Extremely low resistance in an injector solenoid (injector shorted internally but not toground)
4) Malfunctioning or damaged ECM.

Possible causes of multiple injector fault codes in the same bank of injectors include:
1) Short circuit in the engine harness(es) – either shorts to ground or to other wires in the engine harness
2) Short circuit in any of the three injectors in the bank – shorts to ground Malfunctioning or damaged ECM.

Same Bank Fault Codes:
1) Bank 1 – Front Bank: Fault Codes 322, 324, 331
2) Bank 2 – Rear Bank: Fault Codes 323, 325, 332

Reason:
Aftertreatment Diesel Oxidation Catalyst Intake Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level. The diesel oxidation catalyst intake temperature sensor reading has exceeded the maximum temperature limit.

Effect:
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamps starts flashing.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel oxidation catalyst intake temperature sensor is located in the aftertreatment system. It is located at the intake of the aftertreatment catalyst. Refer to the OEM service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the temperature at the diesel oxidation catalyst intake was greater than 687°C [1269°F] for 60 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) A default value for the aftertreatment diesel oxidation catalyst intake temperature sensor reading is used.
3) Active and stationary regeneration of the diesel particulate filter will be disabled.
4) The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel oxidation catalyst and/or aftertreatment diesel particulate filter.

The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damage and reuse. Refer to the OEM service manual.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system

Reason:
Aftertreatment Diesel Oxidation Catalyst Intake Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level. The diesel oxidation catalyst intake temperature sensor reading has exceeded the maximum temperature limit.

Effect:
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamps starts flashing.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel oxidation catalyst intake temperature sensor is located in the aftertreatment system. It is located at the intake of the aftertreatment catalyst. Refer to the OEM service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the temperature at the diesel oxidation catalyst intake was greater than 687°C [1269°F] for 60 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) A default value for the aftertreatment diesel oxidation catalyst intake temperature sensor reading is used.
3) Active and stationary regeneration of the diesel particulate filter will be disabled.
4) The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel oxidation catalyst and/or aftertreatment diesel particulate filter.

The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damage and reuse. Refer to the OEM service manual.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system

Reason:
Aftertreatment Diesel Particulate Filter Intake Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level. The aftertreatment diesel particulate filter intake temperature sensor reading has exceeded the maximum engine protection temperature limit.

Effect:
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamps starts flashing.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter intake temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel oxidation catalyst and before the diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault Codes:
The aftertreatment diesel particulate filter intake temperature sensor reading was greater than 650°C [1202°F] for 85 seconds, or the difference between the diesel oxidation catalyst intake temperature and the diesel particulate filter intake temperature was greater than 365°C [689°F] for 50 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) Active and stationary regeneration of the diesel particulate filter will be disabled.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel particulate filter. This fault will go inactive immediately after the aftertreatment temperatures drop below the warning limit, and will likely be inactive when the vehicle is in the shop. For these reasons, this troubleshooting tree must be used for both active and inactive fault codes.

The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damaged and reuse. Refer to the OEM service manual.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system
3) A face plugged aftertreatment diesel oxidation catalyst

Reason:
Aftertreatment Diesel Particulate Filter Intake Temperature – Data Valid But Above Normal Operating Range – Moderately Severe Level. The aftertreatment diesel particulate filter intake temperature sensor reading has exceeded the maximum engine protection temperature limit.

Effect:
Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamps starts flashing.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter intake temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel oxidation catalyst and before the diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Conditions for Setting the Fault Codes:
The aftertreatment diesel particulate filter intake temperature sensor reading was greater than 650°C [1202°F] for 85 seconds, or the difference between the diesel oxidation catalyst intake temperature and the diesel particulate filter intake temperature was greater than 365°C [689°F] for 50 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) Active and stationary regeneration of the diesel particulate filter will be disabled.
3) Exhaust Gas Recirculation (EGR) valve operation will be disabled.
4) The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault code is logged when the ECM has detected a high temperature condition in the aftertreatment system and active regeneration of the aftertreatment diesel particulate filter is not occurring. The fault code indicates that a secondary fuel source is entering the aftertreatment system and is creating a temperature increase across the aftertreatment diesel particulate filter. This fault will go inactive immediately after the aftertreatment temperatures drop below the warning limit, and will likely be inactive when the vehicle is in the shop. For these reasons, this troubleshooting tree must be used for both active and inactive fault codes.

The aftertreatment system must be inspected after making the appropriate repair outlined in this fault code troubleshooting tree. Progressive damage to the aftertreatment system may have occurred. Remove the exhaust aftertreatment system from the vehicle to inspect it for potential damaged and reuse. Refer to the OEM service manual.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system
3) A face plugged aftertreatment diesel oxidation catalyst

Reason:
Aftertreatment Diesel Particulate Filter Intake Temperature – Data Valid But Above Normal Operating Range – Least Severe Level. The aftertreatment diesel particulate filter intake temperature sensor reading has exceeded the maximum engine protection temperature limit.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel particulate filter temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment diesel partculate filter temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link. The aftertreatment diesel particulate filter temperature sensor module is used to measure the aftertreatment diesel oxidation catalyst intake temperature, aftertreatment diesel particulate filter intake temperature, and aftertreatment diesel particulate filter outlet temperature. The temperature probes are permanently attached to the aftertreatment diesel particulate filter temperature sensor module and can not be replaced individually.

Component Location:
The aftertreatment diesel particulate filter intake temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel oxidation catalyst and before the diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position and the engine is running.

Conditions for Setting the Fault Codes:
The aftertreatment diesel particulate filter intake temperature sensor reading was greater than 675°C [1247°F] for 5 seconds on five separate occasions.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) Active and stationary regeneration of the diesel particulate filter will be disabled.
3) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, start the engine and perform the INSITE™ electronic service tool Aftertreatment Diesel Particulate Filter Regeneration Test.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
This fault will go inactive immediately after the aftertreatment temperatures drop below the warning limit, and will likely be inactive when the vehicle is in the shop. For these reasons, this troubleshooting tree must be used for both active and inactive fault codes.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

Possible Causes:
1) Excessive engine oil or diesel fuel being introduced into the exhaust system from the engine
2) A damaged engine fuel injector causing unburned diesel fuel to enter the exhaust system
3) A face plugged aftertreatment diesel oxidation catalyst