FAIRLEAD ASSEMBLY 1187211 - Caterpillar

this procedure to troubleshoot a high oxygen level in the Clean Emissions Module (CEM). Also, use this procedure if one of the following event codes is active or logged.
Table 1
J1939 Code and Description CDL Code and Description Comments
3217-16
Aftertreatment #1 Intake O2 : Low - least severe (1) E1407(2)
High Aftertreatment #1 Intake O2 Concentration The NOx sensors are detecting a higher than normal oxygen concentration.
3227-16
Aftertreatment #1 Outlet O2 : Low - least severe (1) E1408(2)
High Aftertreatment #1 Outlet O2 Concentration The NOx sensors are detecting a higher than normal oxygen concentration. The engine out NOx sensor is located on the mixer assembly between the turbocharger outlets and the inlet to the CEM.The tailpipe out NOx sensor is located on the outlet of the CEM.Probable Causes
Sensor
Leaks
CodesRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Verify that the NOx Sensors are Installed
A. Locate the appropriate NOx Sensor.
B. Check if the sensor is installed properly.
Sensor
Result: The sensor is not installed properly.
Repair: Install the sensor properly.
Proceed to Test Step 4.
Result: The sensor is installed properly.
Proceed to Test Step 2.
2. Check for Exhaust Leaks
A. Start the engine.
B. Check the exhaust system for proper installation.
C. Check for loose or broken exhaust joints.
D. Inspect the exhaust system between the turbocharger outlet and the tailpipe outlet for signs of an exhaust leak.
Leaks
Result: An exhaust leak was not found.
Proceed to Test Step 3.
Result: An exhaust leak was found.
Repair: Repair or replace damaged exhaust component.
If the problem is not resolved, proceed to Test Step 3.
3. Replace the Failed NOx Sensor
A. Remove electrical power from the engine.
B. Replace the failed NOx sensor.
Sensor
Result: The NOx sensor was replaced.
Proceed to Test Step 4.
4. Operate the Engine
A. Apply electrical power to the engine.
B. Start the engine.
C. Run the engine until normal operating temperature is reached.
D. Connect Cat® Electronic Technician (ET) to the service tool connector.
E. Use Cat ET to monitor the following:
- Codes
Codes
Result: A code is not active.
Return to service.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).