P249E
DTC P249D or P249E
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 P249D
- Closed Loop Reductant Injection Control At Limit - Flow Too Low
DTC P249E
- Closed Loop Reductant Injection Control At Limit - Flow Too High
Diagnostic Fault Information
Circuit/System Description
The selective catalytic reduction (SCR) system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid (DEF) or reductant into the exhaust gas stream entering the SCR catalyst. Within the SCR catalyst, the DEF reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the engine control module (ECM) with engine-out and tailpipe-out NOx levels. The ECM varies the amount of DEF added by varying the reductant injector duty-cycle in response to changes in engine-out NOx levels.
The ECM supplies voltage to the reductant injector on the injector high control circuit. The ECM turns ON the reductant injector by grounding the low control circuit of the injector.
Conditions for Running the DTCs
* DTCs P0101, P0401, P0402, P0420, P11DB, P11DC, P140B, P140C, P207F, P2200, P2202, P2203, P2205, P2209, P229E, P229F, P22A3, P22A7, or U029D, or U029E are not set
* SCR reductant level not in restriction or empty level state
* The engine speed is greater than 600 RPM.
* The battery voltage is greater than 11 V.
* The ambient air and emission reduction fluid tank temperatures are warmer than -7°C (19°F).
* The engine run time is greater than 10 s.
* The DTCs run continuously once the above conditions are met.
Conditions for Setting the DTC
The ECM detects an out of range high or low dosing control factor.
Action Taken When the DTC Sets
DTCs P249D and P249E are Type B DTCs.
Conditions for Clearing the DTC
DTCs P249D and P249E are Type B DTCs.
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)
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify there are no DTCs set related to the following systems or components:
* Diesel exhaust fluid system
* Engine misfire
* Exhaust gas recirculation
* Exhaust gas temperature sensors
* Fuel system - low or high pressure
* Indirect fuel injector
* Intake air flow valve
* MAF sensor
* NOx or HO2S sensors
* Turbocharger system
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.
2. Test the diesel exhaust fluid for contamination. Refer to Contaminants-in-Diesel Exhaust Fluid Diagnosis (Contaminants-in-Diesel Exhaust Fluid Diagnosis).
• If the diesel exhaust fluid is contaminated, replace the diesel exhaust fluid.
3. Ignition ON, command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build for 30 s. Verify there are no leaks in the reductant lines.
• If a condition is found, repair as necessary.
4. Remove the Q61 emission reduction fluid injector from the exhaust pipe leaving the reductant line and electrical connector connected. Place the Q61 emission reduction fluid injector into a suitable container.
5. Command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build for 30 s. The Q61 emission reduction fluid injector should not leak.
• If a condition is found, replace the Q61 emission reduction fluid injector.
6. Perform the Emission Reduction Fluid Injector Quantity Test (Emission Reduction Fluid Injector Quantity Test). The Q61 emission reduction fluid injector should pass the test.
• If the injector fails the test, replace the Q61 emission reduction fluid injector.
7. Verify the following conditions do not exist:
* Q57 Indirect fuel injector leaking or restricted-Refer to Indirect Fuel Injector Diagnosis (Indirect Fuel Injector Diagnosis)
* Leaking fuel injectors
* Engine oil or coolant consumption
* Engine mechanical condition
• If a condition is found, repair as necessary
8. Verify the following conditions do not exist with the SCR:
* Physical damage or alterations
* Internal rattles caused by a damaged catalyst substrate
* Leaks in the exhaust system-Refer to Exhaust Leakage (Exhaust Leakage) for further diagnosis.
• If a condition is found, repair as necessary.
9. If all components and fluid test normal, replace the SCR.
Repair Instructions
* Emission Reduction Fluid Exhaust Front Pipe Injector Supply Pipe Replacement (Service and Repair)
* Emission Reduction Fluid Injector Replacement (Service and Repair)
* Emission Reduction Fluid Tank Replacement (Emission Reduction Fluid Tank Replacement)
* Exhaust Particulate Filter Replacement (LMM) (Service and Repair) Exhaust Particulate Filter Replacement (20 Series) (Service and Repair) Exhaust Particulate Filter Replacement (35 Series) (Service and Repair)
* Perform the following scan tool reset procedures after replacing the DEF or any other components not including the SCR/DPF:
1. NOx Catalyst Reductant Loading Reset
2. Diesel Particulate Filter (DPF) Service Regeneration (Diesel Particulate Filter (DPF) Service Regeneration)
3. Reductant Fluid Quality Test. This test is necessary to reset the Reductant System history. Disregard the test results.
* Perform the following scan tool reset procedures after replacing the SCR/DPF:
1. NOx Catalyst Reductant Loading Reset
2. NOx Catalyst Reset
3. DPF/Catalyst 2 Reset
4. Reductant Fluid Quality Test. This test is necessary to reset the Reductant System history. Disregard the test results.
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 90 km/h (55 mph) with this speed maintained until the average SCR temperature is between 240-290°C (464-554°F).