GASKET KIT ENG 5P4821 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the NOX sensor group. Also, use this procedure if one of the diagnostic codes or the event code in Table 1 is active or easily repeated.
Table 1
J1939 Code and Description Comments
3226-2
Aftertreatment #1 Outlet 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.
3226-12
Aftertreatment #1 Outlet NOx : Failure During a self-test, the NOx sensor has detected an internal fault.
Replace the sensor
The code is logged.
3226-14
Aftertreatment #1 Outlet NOx : Special Instruction The NOx sensor has detected an internal problem with the sensor heating element. The sensor was unable to reach operating temperatures within the predetermined amount of time.
5759-6
Aftertreatment #1 Outlet 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.
5759-11
Aftertreatment #1 Outlet 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 is powered by a (100 % ON) Pulse Width Modulated output (PWM output). The ECM is the power source. The sensor buffer requires 18 V to 36 V to operate.The sensor and the sensor buffer are integrated parts. The sensor and the sensor buffer must be replaced as a single component, if necessary.NOx Sensor Power Supply Enablement ConditionsA Cat ET service test, for overriding the power supply may be available for diagnostic testing purposes. If an override is unavailable, starting and running the engine in accordance with the sensor buffer power-on requirements will be necessary.The buffer is powered by the ECM after the following conditions are verified:
No diagnostic codes related to the NOX sensor are active
Engine speed above 500 rpm
Engine