C3.4B Engines Caterpillar

NOx Sensor - Test

Usage:

CCS7 4B2

This procedure covers the following codes:

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Table 1
Diagnostic Trouble Codes for the NOx Sensors
J1939 Code	Description	Notes
3216-2	Aftertreatment #1 Intake NOx : Erratic, Intermittent, or Incorrect	The Electronic Control Module (ECM) detects one of the following conditions: The signal from the engine out NOx sensor is invalid. The sensor supply to the engine out NOx sensor is faulty. The warning lamp will come on. The warning lamp may flash. The engine may be derated.
3216-5	Aftertreatment #1 Intake NOx : Current Below Normal	The ECM detects an open circuit error message from the engine out NOx sensor for at least 2 seconds. The warning lamp will come on.
3216-6	Aftertreatment #1 Intake NOx : Current Above Normal	The ECM detects a short circuit error message from the engine out NOx sensor for at least 2 seconds. The warning lamp will come on.
3216-10	Aftertreatment #1 Intake NOx : Abnormal Rate of Change	The ECM detects that the difference between the oxygen signal from the engine out NOx sensor and the calculated oxygen level is to great. The warning lamp will come on.
3216-19	Aftertreatment #1 Intake NOx : Data Error	The ECM detects a loss of communication with the engine out NOx sensor for at least 0.5 seconds. The warning lamp will come on.
3226-2	Aftertreatment #1 Outlet NOx : Erratic, Intermittent, or Incorrect	The ECM detects one of the following conditions: The signal from the tailpipe out NOx sensor is invalid. The sensor supply to the tailpipe out NOx sensor is faulty. The warning lamp will come on. The warning lamp may flash. The engine may be derated.
3226-5	Aftertreatment #1 Outlet NOx : Current Below Normal	The ECM detects an open circuit error message from the tailpipe out NOx sensor for at least 2 seconds. The warning lamp will come on.
3226-6	Aftertreatment #1 Outlet NOx : Current Above Normal	The ECM detects a short circuit error message from the tailpipe out NOx sensor for at least 2 seconds. The warning lamp will come on.
3226-7	Aftertreatment #1 Outlet NOx : Not Responding Properly	The ECM detects that the amount of NOx measured by the tailpipe out NOx sensor does not vary enough to be a plausible signal The warning lamp will flash. The engine will be derated.
3226-10	Aftertreatment #1 Outlet NOx : Abnormal Rate of Change	The ECM detects that the difference between the oxygen signal from the tailpipe out NOx sensor and the calculated oxygen level is to great. The warning lamp will come on.
3226-19	Aftertreatment #1 Outlet NOx : Data Error	The ECM detects a loss of communication with the tailpipe out NOx sensor for at least 0.5 seconds. The warning lamp will come on.
3226-21	Aftertreatment #1 Outlet NOx : Data Drifted Low	The ECM detects a negative value for the NOx signal from the engine out NOx sensor. The warning lamp will flash. The engine will be derated.
5024-5	Aftertreatment 1 Intake NOx Sensor Heater Ratio : Current Below Normal	The ECM detects an open circuit error message for the heater circuit on the engine out NOx sensor for at least 2 seconds. The warning lamp will flash. The engine will be derated.
5024-6	Aftertreatment 1 Intake NOx Sensor Heater Ratio : Current Above Normal	The ECM detects a short circuit error message for the heater circuit on the engine out NOx sensor for at least 2 seconds. The warning lamp will flash. The engine will be derated.
5024-7	Aftertreatment 1 Intake NOx Sensor Heater Ratio : Not Responding Properly	The ECM detects that the engine out NOx sensor has not reached operating temperature after 3 minutes of heater operation. The warning lamp will come on.
5031-5	Aftertreatment 1 Outlet NOx Sensor Heater Ratio : Current Below Normal	The ECM detects an open circuit error message for the heater circuit on the tailpipe out NOx sensor for at least 2 seconds. The warning lamp will flash. The engine will be derated.
5031-6	Aftertreatment 1 Outlet NOx Sensor Heater Ratio : Current Above Normal	The ECM detects a short circuit error message for the heater circuit on the tailpipe out NOx sensor for at least 2 seconds. The warning lamp will flash. The engine will be derated.
5031-7	Aftertreatment 1 Outlet NOx Sensor Heater Ratio : Not Responding Properly	The ECM detects that the engine out NOx sensor has not reached operating temperature after 3 minutes of heater operation. The warning lamp will come on.

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Illustration 1	g03729172
Schematic diagram for the NOx sensors Not all connectors are shown. Refer to the Electrical Schematic for the application.

Note: The "ADDRESS" wire that is connected to the engine out NOx sensor is used by the ECM to differentiate the signal from the engine out NOx sensor and the tailpipe out NOx sensor.

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Illustration 2	g03729557
View of the pin locations on the P1 connector for the NOx sensors. (23) J1939 CAN 2 + (45) J1939 CAN 2 -

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Check the fuses. B. Thoroughly inspect the connectors for the NOx sensors. Refer to Troubleshooting, "Electrical Connector - Inspect" for details. C. Thoroughly inspect the P1/J1 ECM connector . Refer to Troubleshooting, "Electrical Connector - Inspect" for details. D. Perform a 30 N (6.7 lb) pull test on each of the wires that are associated with the NOx sensors.	Damaged wire or connector	Result: A damaged wire or damaged connector was found. A fuse is blown. Repair: Repair the damaged wire or the damaged connector. Replace any blown fuses. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, of abrasion or of pinch points. The fuses are OK. Proceed to Test Step 2.
2. Check for Diagnostic Codes A. Turn the keyswitch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the keyswitch to the ON position. D. Monitor the electronic service tool for active diagnostic codes and/or logged diagnostic codes.	Diagnostic codes	Result: A diagnostic code other than those listed in Table 1 is active or recently logged. Repair: Troubleshoot the other diagnostic codes before returning to this procedure. Refer to Troubleshooting, "Diagnostic Trouble Codes". Result: One of the diagnostic listed in Table 1 is active or recently logged. Proceed to Test Step 3. Result: None of the diagnostic codes listed in Table 1 are active or recently logged. Repair: The fault may be intermittent. Refer to Troubleshooting, "Electrical Connector - Inspect" in order to identify intermittent faults.
3. Inspect the Exhaust System for Leaks A. Thoroughly inspect the exhaust system for leaks. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System - Inspect".	Exhaust leaks	Result: There is a leak in the exhaust system. Repair: Make any necessary repairs. Run the engine. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The exhaust system is OK. Proceed to Test Step 4.
4. Inspect the NOx Sensors A. Inspect the NOx sensors for damage. B. Check that the NOx sensors are mounted in the correct position. C. Ensure that the NOx sensors are mounted securely	NOx sensors	Result: Fault found with the NOx sensors. Repair: Make any necessary repairs. If necessary, replace a damaged NOx sensor. Refer to Disassembly and Assembly, "Nitrogen Oxide Sensor - Remove and Install" for the correct procedure. Run the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The NOx sensors are mounted securely and not damaged. Proceed to Test Step 5.
5. Check the Address Switch Wiring for the Engine Out NOx Sensor Note: The "ADDRESS" wire that is connected to the engine out NOx sensor is used by the ECM to differentiate the signal from the engine out NOx sensor and the tailpipe out NOx sensor. A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector for the engine out NOx sensor. C. Use a multimeter to measure the resistance between terminal 5 on the harness connector and a suitable engine ground.	Less than 5 Ohms	Result: The measured resistance is greater than 5 Ohms. The fault is in the address wiring for the engine out NOx sensor. Repair: Replace the faulty wiring. Run the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The measured resistance is less than 5 Ohms. Proceed to Test Step 6.
6. Check the Power Supply at the Suspect NOx Sensor A. Turn the keyswitch to the OFF position. B. Disconnect the connectors for the NOx sensors. C. Turn the keyswitch to the ON position. D. Use a multimeter to measure the voltage between terminal 1 and terminal 2 on the harness connector for each sensor. E. Turn the keyswitch to the OFF position.	10 V to 14 V	Result: Both voltage measurements are not within the expected range. Repair: Install a replacement auxiliary main relay. Run the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: One of the voltage measurements is not within the expected range. The fault is in the power supply or ground wiring for the suspect sensor. Repair: Replace the faulty wiring. Run the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: Both voltage measurements are within the expected range. Proceed to Test Step 7.
7. Check the CAN Data Link A. Check the CAN data link for faults. Refer to Troubleshooting, "CAN Data Link - Test".	CAN Data Link	Result: A fault was found on the CAN data link. Repair: Make any necessary repairs. Run the engine. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: The CAN data link is OK. Repair: Install a replacement for the suspect NOx sensor. Refer to Disassembly and Assembly, "Nitrogen Oxide Sensor - Remove and Install" for the correct procedure.
If the procedure did not correct the fault, contact the Dealer Solution Network (DSN).