CYL HEAD A 0R0830 - Caterpillar

This procedure covers the following codes:
Table 1
Diagnostic Trouble Codes for the Ammonia Sensor
J1939 Code Description Notes
4377-2 Aftertreatment 1 Outlet NH3 : Erratic, Intermittent, or Incorrect The Electronic Control Module (ECM) detects an open or short circuit error message for one of the ammonia sensor measuring cell lines for at least 12 seconds.
The warning lamp will flash. The engine will be derated.
4377-4 Aftertreatment 1 Outlet NH3 : Voltage Below Normal The ECM detects an open circuit error message for the signal ground line of the ammonia sensor for at least 2 seconds.
The warning lamp will flash. The engine will be derated.
4377-7 Aftertreatment 1 Outlet NH3 : Not Responding Properly The ECM detects an open or short circuit error message for the temperature cell input line or the trim resistor line input of the ammonia sensor for at least 2 seconds.
The warning lamp will flash. The engine will be derated.
4377-12 Aftertreatment 1 Outlet NH3 : Failure The ECM detects an invalid signal from the ammonia sensor for at least 2 seconds.
The warning lamp will flash. The engine will be derated.
4377-19 Aftertreatment 1 Outlet NH3 : Data Error The ECM detects a loss of signal from the ammonia sensor for at least 0.5 seconds.
The warning lamp will come on.
4377-20 Aftertreatment 1 Outlet NH3 : Data Drifted High The ECM detects that the sensor signal has drifted outside of the acceptable values for at least 20 seconds.
The warning lamp will flash. The engine will be derated.
4383-5 Aftertreatment 1 Outlet NH3 Gas Sensor Heater Control : Current Below Normal The ECM detects a low current condition on the ammonia sensor heater circuit for at least 2 seconds.
The warning lamp will flash. The engine will be derated.
4383-6 Aftertreatment 1 Outlet NH3 Gas Sensor Heater Control : Current Above Normal The ECM detects a high current condition on the ammonia sensor heater circuit for at least 2 seconds.
The warning lamp will flash. The engine will be derated.
4383-7 Aftertreatment 1 Outlet NH3 Gas Sensor Heater Control : Not Responding Properly The ECM detects an error message from the ammonia sensor for the sensor heater circuit at least 15 seconds.
The warning lamp will flash. The engine will be derated.
Illustration 1 g03731618
Schematic diagram for the ammonia sensor
Not all connectors are shown. Refer to the Electrical Schematic for the application.
Illustration 2 g03729557
View of the pin locations on the P1 connector for the ammonia sensor.
(23) J1939 CAN 2 +
(45) J1939 CAN 2 -
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Check the fuses.
B. Thoroughly inspect the connectors for the ammonia sensor. 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 ammonia sensor.
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