P20A2
DTC P1045, P1046, P20A0, P20A2, or P20A3
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P1045
- Reductant Purge Valve High Control Circuit Low Voltage
DTC P20A0
- Reductant Purge Valve Control Circuit
DTC P20A2
- Reductant Purge Valve Control Circuit Low Voltage
DTC P20A3
- Reductant Purge Valve Control Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The reductant purge valve controls the flow of diesel exhaust fluid (DEF). In the normally de-energized state, the purge valve directs reductant from the pump to the reductant injector. When the ignition is turned OFF, the engine control module (ECM) energizes both the reductant purge valve and reductant pump for about 30 to 45 seconds to purge the supply line of reductant. The ECM also commands the DEF injector to 100% to prevent vacuum from forming during the purge process. Purging prevents the reductant from freezing in the pump or supply line to the reductant injector. The ECM will set a DTC when an abnormal voltage condition on the purge valve circuit is detected.
The ECM provides battery voltage on the actuator high control circuit and ground on the actuator low control circuit. Both circuits are controlled through output drivers within the ECM. The ECM monitors the voltage on the circuits to detect a failure.
Conditions for Running the DTC
* The battery voltage is greater than 11 V.
* The engine speed is greater than 600 RPM.
* The engine run time is greater than 10 s.
* The DTCs run continuously when the above conditions are met.
Conditions for Setting the DTC
P1045 or P20A3
When the solenoid is commanded ON, the ECM detects the commanded state of the driver and the actual state of the control circuits do not match for greater than 3 s.
P20A0 or P20A2
When the solenoid is commanded OFF, the ECM detects the commanded state of the driver and the actual state of the control circuits do not match for greater than 3 s.
Action Taken When the DTC Sets
DTC P1045, P20A0, P20A2, and P20A3 are Type B DTCs
The ECM inhibits the reductant system when DTC P1045 or P20A2 is set.
Conditions for Clearing the DTC
DTC P1045, P20A0, P20A2, or P20A3 is a Type B DTC
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
* Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level) (Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level)) Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality) (Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality)) Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering) (Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering))
* Exhaust Aftertreatment System Description (Emission Control Systems)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, command the Reductant Purge Valve ON and OFF with a scan tool. You should hear an audible click.
2. Ignition ON, command the Reductant Purge Valve ON and OFF with a scan tool while observing the Reductant Purge Vlv Ctrl Ckt Status parameter. The parameter should display OK or Not Run.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the 24-way harness connector at the DEF Tank. Refer to Inline Harness Connector End Views (Connector End Views By Number) for connector identification.
Note: Testing for steps 2-5 is performed on the ECM side of the harness connector.
2. Ignition ON, test for 2.5-4.5 V between the DEF reverting valve high control circuit terminal A7 and ground.
• If less than the specified range, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the high control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
3. Command the Reductant Purge Valve ON and OFF with a scan tool. The DMM should transition from 2.5-4.5 V when commanded OFF to greater than 10 V, when commanded ON.
• If the circuit voltage does not correspond to the specified values, replace the K20 ECM.
4. Test for 2.5-4.5 V between the DEF reverting valve low control circuit terminal B7 and ground.
• If less than the specified range, test the low control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the low control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. Command the Reductant Purge Valve ON and OFF with a scan tool. The DMM should transition from 2.5-4.5 V when commanded OFF to less than 2 V, when commanded ON.
• If the circuit voltage does not correspond to the specified values, replace the K20 ECM.
Note: Testing for this step is performed on the DEF tank side of the harness connector.
6. Remove the DEF tank and test, inspect, and repair the items listed below. If all items test normal, replace the Q62 reductant purge valve.
* Poor connection at the 24-way harness connector
* Open or shorted DEF reverting valve high control circuit
* Open or shorted DEF reverting valve low control circuit
Repair Instructions
* Emission Reduction Fluid Tank Replacement (Emission Reduction Fluid Tank Replacement)
* Perform the scan tool Reductant System Reset procedure after replacing the emission reduction fluid tank.
* Control Module References (Programming and Relearning) for engine control module replacement, programming, and setup
Repair Verification
1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes.
Note: The diesel exhaust fluid (DEF) and ambient air temperatures must be greater than -7°C (19°F) before proceeding with this procedure.
5. Ignition ON, command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build for 30 s. Observe the scan tool Reductant Pressure sensor parameter. The reading should be between 425-575 kPa and there should be no leaks in the system.
Warning
Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
6. Engine idling at operating temperature. Accelerate at part throttle to 32-48 km/h (20-30 mph) for up to 5 minutes or until the DEF lamp turns OFF. The DEF lamp should turn OFF.
• If the DEF lamp does not turn OFF, a condition with the system still exists.