Volvo

When the aftertreatment selective catalytic reduction (SCR) system operates under normal conditions, the aftertreatment control module (ACM) monitors diesel exhaust fluid (DEF) dosing valve duty cycle and DEF pump control value. When the DEF dosing valve duty cycle increases above allowed threshold and the DEF pump control value decreases below expected threshold, the ACM stops DEF dosing and reports a fault. The fault might be indication of electrical failure or blockage in DEF dosing valve or DEF supply line from the DEF tank.

Conditions for diagnostic trouble code (DTC):
1) Short circuit to ground

Observable symptoms
1) No aftertreatment diesel exhaust fluid (DEF) dosage

Probable cause
1) Connector
2) Wiring harness
3) Aftertreatment diesel exhaust fluid (DEF) dosage valve
4) Dosage electronic control unit (ECU), pump unit

When the aftertreatment selective catalytic reduction (SCR) system operates under normal conditions, the aftertreatment control module (ACM) monitors diesel exhaust fluid (DEF) dosing valve duty cycle and DEF pump control value. When the DEF dosing valve duty cycle increases above allowed threshold and the DEF pump control value decreases below expected threshold, the ACM stops DEF dosing and reports a fault. The fault might be indication of electrical failure or blockage in DEF dosing valve or DEF supply line from the DEF tank.

Conditions for diagnostic trouble code (DTC):
1) Open circuit

Observable symptoms
1) No aftertreatment diesel exhaust fluid (DEF) dosage

Probable cause
1) Connector
2) Wiring harness
3) Aftertreatment diesel exhaust fluid (DEF) dosage valve
4) Dosage electronic control unit (ECU), pump unit

When the aftertreatment selective catalytic reduction (SCR) system operates under normal conditions, the aftertreatment control module (ACM) monitors diesel exhaust fluid (DEF) dosing valve duty cycle and DEF pump control value. When the DEF dosing valve duty cycle increases above allowed threshold and the DEF pump control value decreases below expected threshold, the ACM stops DEF dosing and reports a fault. The fault might be indication of electrical failure or blockage in DEF dosing valve or DEF supply line from the DEF tank.

Conditions for diagnostic trouble code (DTC):
1) Mechanical fault

Observable symptoms
1) No aftertreatment diesel exhaust fluid (DEF) dosage

Probable cause
1) Aftertreatment diesel exhaust fluid (DEF) dosage valve

The Engine Control Module (ECM) monitors the crankshaft angular acceleration using the flywheel sensor. The ECM monitors the camshaft position sensor to determine the engine?s position. The ECM calculates the average value of crankshaft angular acceleration for all six cylinders and compares the value to each individual cylinder?s angular acceleration. If a cylinder?s acceleration value is outside a specified range the ECM interprets this as a misfiring cylinder. The crankshaft average angular acceleration value is used by the ECM to determine cylinder balancing and idle speed.

Conditions for diagnostic trouble code (DTC):
1) Calculated fuel consumption, Above normal

Observable symptoms
1) High fuel consumption

Probable cause
1) Power Take Off (PTO) installed without updating parameters and/or software
2) Parameter code, unit injector
3) Fuel
4) Injector

This diagnostic function detects if the regeneration frequency increases to a level such that it would cause the emissions to exceed the OBD threshold or if the frequency exceeds the design requirements.
The number of completed regenerations during a defined time period is counted. If the number of regenerations are above threshold at the end of the time period fault is reported.

Conditions for diagnostic trouble code (DTC):
1) Regeneration successful but too frequent

Observable symptoms
1) DPF Regeneration too frequent

Probable cause
1) Aftertreatment DPF Differential Pressure Sensor
2) EGR System
3) Aftertreatment diesel particulate filter (DPF) is damaged, soot loaded or missing
4) Excessive ash in DPF

The Aftertreatment Hydrocarbon Dosing Module contains three non serviceable valves, the Aftertreatment Fuel Shutoff Valve, Aftertreatment Purge Air Valve and Aftertreatment Hydrocarbon Dosing Valve, and a serviceable Aftertreatment Fuel Pressure Sensor.
During DPF regeneration the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Fuel Shutoff Valve to the open position. This allows fuel to flow into the Aftertreament Hydrocarbon Dosing Module. The Aftertreatment Fuel Pressure Sensor monitors the fuel pressure value and sends a reference signal to the ECM. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that regulates the amount of fuel delivered to the Aftertreatment Hydrocarbon Doser through the air/fuel line.
During Air Purge operation the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Purge Air Valve open. This allows air pressure to flow into the Aftertreament Hydrocarbon Dosing Module. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that allows purge air pressure to be monitored by a signal from the Aftertreatment Fuel Pressure Sensor to the ECM.

Observable symptoms
1) Regeneration not possible

Probable cause
1) Fuel line(s)
2) Obstructed/dirty aftertreatment hydrocarbon doser
3) Aftertreatment Hydrocarbon Dosing Module

The Aftertreatment Hydrocarbon Dosing Module contains three non serviceable valves, the Aftertreatment Fuel Shutoff Valve, Aftertreatment Purge Air Valve and Aftertreatment Hydrocarbon Dosing Valve, and a serviceable Aftertreatment Fuel Pressure Sensor.
During DPF regeneration the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Fuel Shutoff Valve to the open position. This allows fuel to flow into the Aftertreament Hydrocarbon Dosing Module. The Aftertreatment Fuel Pressure Sensor monitors the fuel pressure value and sends a reference signal to the ECM. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that regulates the amount of fuel delivered to the Aftertreatment Hydrocarbon Doser through the air/fuel line.
During Air Purge operation the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Purge Air Valve open. This allows air pressure to flow into the Aftertreament Hydrocarbon Dosing Module. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that allows purge air pressure to be monitored by a signal from the Aftertreatment Fuel Pressure Sensor to the ECM.

Conditions for diagnostic trouble code (DTC):
1) Air pressure, not within expected range

Observable symptoms
1) Regeneration not possible

Probable cause
1) Low air pressure
2) Aftertreatment Hydrocarbon Dosing Module
3) Inconsistent Air pressure
4) Fuel line(s), Leakage
5) Aftertreatment Fuel Pressure Sensor

The Aftertreatment Hydrocarbon Dosing Module contains three non serviceable valves, the Aftertreatment Fuel Shutoff Valve, Aftertreatment Purge Air Valve and Aftertreatment Hydrocarbon Dosing Valve, and a serviceable Aftertreatment Fuel Pressure Sensor.
During DPF regeneration the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Fuel Shutoff Valve to the open position. This allows fuel to flow into the Aftertreament Hydrocarbon Dosing Module. The Aftertreatment Fuel Pressure Sensor monitors the fuel pressure value and sends a reference signal to the ECM. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that regulates the amount of fuel delivered to the Aftertreatment Hydrocarbon Doser through the air/fuel line.
During Air Purge operation the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Purge Air Valve open. This allows air pressure to flow into the Aftertreament Hydrocarbon Dosing Module. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that allows purge air pressure to be monitored by a signal from the Aftertreatment Fuel Pressure Sensor to the ECM.

Conditions for diagnostic trouble code (DTC):
1) Aftertreatment Fuel Pressure, not within expected range
2) Fuel pressure fault

Observable symptoms
1) Regeneration not possible

Probable cause
1) Fuel pressure
2) Fuel line(s)
3) Aftertreatment Hydrocarbon Dosing Module

The Aftertreatment Hydrocarbon Dosing Module contains three non serviceable valves, the Aftertreatment Fuel Shutoff Valve, Aftertreatment Purge Air Valve and Aftertreatment Hydrocarbon Dosing Valve, and a serviceable Aftertreatment Fuel Pressure Sensor.
During DPF regeneration the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Fuel Shutoff Valve to the open position. This allows fuel to flow into the Aftertreament Hydrocarbon Dosing Module. The Aftertreatment Fuel Pressure Sensor monitors the fuel pressure value and sends a reference signal to the ECM. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that regulates the amount of fuel delivered to the Aftertreatment Hydrocarbon Doser through the air/fuel line.
During Air Purge operation the Engine Control Module (ECM) sends a voltage signal to activate the Aftertreatment Purge Air Valve open. This allows air pressure to flow into the Aftertreament Hydrocarbon Dosing Module. The ECM then sends a PWM signal to the Aftertreatment Hydrocarbon Dosing Valve that allows purge air pressure to be monitored by a signal from the Aftertreatment Fuel Pressure Sensor to the ECM.

Observable symptoms
1) Regeneration not possible

Probable cause
1) Fuel line(s)
2) Component (Pressure regulator) is damaged or missing
3) Aftertreatment Fuel Pressure Sensor
4) Obstructed/dirty aftertreatment hydrocarbon doser
5) Aftertreatment Hydrocarbon Dosing Module