P20EE
DTC P20EE or P2BAD
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 provide an overview of each diagnostic category.
DTC Descriptors
DTC P20EE
- NOx Catalyst Efficiency Below Threshold
DTC P2BAD
- Exhaust NOx Concentration High-Unknown Reason
Circuit/System Description
The ECM uses two nitrogen oxide (NOx) sensors to control exhaust NOx levels. The NOx sensor measures the amount of NOx and oxygen in the exhaust system. The first NOx sensor is located at the outlet of the turbocharger and monitors the engine out NOx. The second NOx sensor is located between the selective catalytic reduction (SCR) and the diesel particulate filter (DPF) that monitors NOx levels exiting the SCR. The engine control module (ECM) varies the amount of diesel exhaust fluid (DEF) or reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out NOx levels.
Conditions for Running the DTC
* The BARO pressure is greater than 75 kPa (11 psi).
* The ambient air and reductant temperatures are warmer than -7°C (19°F) and the reductant tank is not frozen.
* The engine speed is between 1,000-3,000 RPM.
* The average SCR temperature is between 240-300°C (464-572°F).
* The emission reduction fluid tank level is not empty.
* The battery voltage is greater than 11 V for more than 3 s.
* The engine run time is greater than 10 s.
* Vehicle speed must be greater than 80 km/h (50 mph) for 5 minutes.
* Vehicle is not in a DPF regeneration.
* Engine on time must be less than 25 minutes.
* The DTCs run once per drive cycle when the above conditions are met.
Conditions for Setting the DTC
The ECM has determined the catalyst efficiency has degraded below a calibrated threshold.
Action Taken When the DTC Sets
* DTC P20EE and P2BAD are Type A DTCs.
* Requires 2 drive cycles to set the DTC.
Conditions for Clearing the DTC
DTC P20EE and P2BAD are Type A DTCs.
Diagnostic Aids
* A leak in the reductant system can be located by inspecting for a build-up of crystallized diesel exhaust fluid (DEF).
* A quality message may be present on the Driver Information Center (DIC) with or without DTCs P20EE or P2BAD.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
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)Diesel Exhaust Fluid (DEF) Warning Strategy (Emission Control) Diesel Exhaust Fluid (DEF) Warning Strategy (Emission Control)
* 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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P0101, P0400, P0401, P0402, P0420, P1043, P1044, P1048, P1049, P11CB, P11CC, P11DB, P11DC, P140B, P140C, P202E, P2047, P2048, P2049, P204B, P204C, P204D, P204F, P205B, P205C, P025D, P208A, P208B, P208D, P20A0, P20A2, P20A3, P20E8, P20E9, P2200, P2201, P2202, P2203, P2205, P2209, P229E, P229F, P22A0, P22A1, P22A3, P22A7, P2413, PC29D, or PC29E are not set.
• 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 at least 2 minutes. The first 60 s, the system performs a system purge. Observe the scan tool Reductant Pressure sensor parameter. The reading should be between 400-650 kPa (58-94 psi) and there should be no leaks in the system.
4. Verify there are no leaks in the reductant lines.
• If a condition is found, repair as necessary.
5. 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.
6. Ignition ON, command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build to at least 400 kPa (58 psi). The Q61 emission reduction fluid injector should not leak.
• If a condition is found, replace the Q61 emission reduction fluid injector.
7. With the Q61 emission reduction fluid injector installed, 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.
8. Verify the following conditions do not exist:
* Leaking Q57 Indirect fuel injector-Refer to Indirect Fuel Injector Diagnosis Indirect Fuel Injector Diagnosis
* Leaking fuel injectors-Refer to Fuel Injector Balance Test with Tech 2 Fuel Injector Balance Test with Tech 2
* Engine oil or coolant consumption
* Engine mechanical condition
• If a condition is found, repair as necessary
9. 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.
* Loose B195 NOx sensors or B131 exhaust temperature sensors-Refer to DTC P11CB-P11CD, P11DB, P11DC, P2201, or P229F P11CB for further diagnosis.
• If a condition is found, repair as necessary.
10. Engine running and at operating temperature, with a scan tool, verify NOx 2 NOx Concentration is less than NOx 1 NOx Concentration.
• If NOx 2 NOx Concentration is greater than NOx 1 NOx Concentration, replace the B195 nitrogen oxide sensor - position 2.
11. Disconnect the Q61 emission reduction fluid injector electrical connector.
12. Idle engine at 1500 RPM for 10 minutes while monitoring NOx 1 and NOx 2 NOx Concentration.
• If NOx 2 NOx Concentration value does not approach NOx 1 Concentration value, replace the B195 nitrogen oxide sensor - position 2.
13. Install any components or connectors that have been removed or replaced during diagnosis.
14. 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 (03 Series) Exhaust Particulate Filter Replacement (03 Series)Exhaust Particulate Filter Replacement (53 Series) Exhaust Particulate Filter Replacement (53 Series)Exhaust Particulate Filter Replacement (43 Series) Exhaust Particulate Filter Replacement (43 Series)
* Nitrogen Oxide Sensor Replacement - Position 2 Nitrogen Oxide Sensor Replacement - Position 2
* 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
Note: The diesel exhaust fluid (DEF) and ambient air temperatures must be greater than -7°C (+19°F) before proceeding with this procedure.
2. Perform the Reductant Fluid Quality Test Reductant Fluid Quality Test. This test may need to be run three consecutive times to insure the Reductant System history resets and has completed estimating the ammonia load. Between each test, ignition OFF, all vehicle systems are completely OFF for at least 2 minutes. This includes retained accessory power (RAP) and the scan tool. Refer to Testing Ground and Low Reference Circuits Testing Ground and Low Reference Circuits for further information.
• If a third test fails, a condition with the system still exists.
* 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. Perform the Reductant Fluid Quality Test Reductant Fluid Quality Test. This test is necessary to reset the Reductant System history. If test fails, perform a second quality test. The test should pass.
• If second test fails, a condition with the system still exists.
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 at least 2 minutes. The first 60 s, the system performs a system purge. Observe the scan tool Reductant Pressure sensor parameter. The reading should be between 400-650 kPa (58-94 psi) and there should be no leaks in the system.
6. Engine idling, verify with a scan tool that NOx 2 NOx Concentration is less than NOx 1 NOx Concentration.
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.
7. 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).