GUARD 9G5845 - Caterpillar

Use this procedure to troubleshoot a problem with the NOx sensor group. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
J1939 Code and Description Comments
3216-2
Aftertreatment #1 Intake NOx : Erratic, Intermittent, or Incorrect The NOx sensor has detected a problem with the stability of the detected NOx level.
The code is active after 3 minutes of continued instability of exhaust NOx levels.
The code is inactive after detected NOx levels return to normal levels for 60 seconds.
3216-4
Aftertreatment #1 Intake NOx : Voltage Below Normal The NOx sensor has detected that the power supply is not in range.
3216-6
Aftertreatment #1 Intake NOx : Current Above Normal The Electronic Control Module (ECM) detects a short in the power supply circuit for the NOx sensor.
The code is logged.
3216-12
Aftertreatment #1 Intake NOx : Failure During a self-test, the NOx sensor has detected an internal fault.
Replace the sensor
The code is logged.
3216-14
Aftertreatment #1 Intake NOx : Special Instruction During a self-test, the NOx sensor has detected an internal fault.
Replace the sensor
The code is logged.
5758-6
Aftertreatment #1 Intake Gas Sensor Power Supply : Current Above Normal The ECM detects a short in the power supply circuit for the NOx sensor.
The code is logged.
5758-11
Aftertreatment #1 Intake Gas Sensor Power Supply : Other Failure Mode The NOx sensor has detected that the power supply is not in range. The NOx sensor group is used by the ECM to measure the level of NOx concentration in the engine exhaust. This value is reported back to the ECM via the CAN data Link. The ECM uses this information to control the air/fuel ratio for the engine. By controlling the air/fuel ratio, the ECM is able to control the engine operation for optimum performance at reduced exhaust emissions.The NOx sensor group is made up of two integrated components:Sensor - The NOx sensor consists of a ceramic element that measures the concentration of NOx in the exhaust gas. The sensor contains a heating element that is used to heat the sensor to approximately 800 °C (1450 °F). Once the heating element reaches this temperature, the sensor begins sending NOx data to the sensor buffer.Sensor buffer - The sensor buffer is used to process the signals that are received from the sensor. The buffer transmits this information to the ECM via the CAN data link. The buffer also reports diagnostic data to the ECM over the CAN data link. The sensor buffer