794 AC Off-Highway Truck Caterpillar

Note: Turn off power supply before disconnecting or connecting the NO_x sensor.

• Inspect harness for damaged wiring

• Inspect for secure connections at all ends of the harness

• Do not contact the sensing element when power is applied to the sensor. Contact with the sensing element may result in injury. The sensing element is heated to a minimum of 100° C (212° F).

• Do not use any lubricant on any part of the sensor other than the threads. Do not use unapproved thread lubricant. Do not apply additional anti-seize to new parts. If additional anti-seize is necessary for pre-installation, use only nickel based anti-seize or non-metallic anti-seize. Apply anti-seize to the threads only and avoid contaminating the sensor head.

• Do not use sensors that have been dropped or have been exposed to other forms of mishandling. Damage to the sensor may have occurred that is not visible.

• Replace the sensor if damaged or faulty.

To replace the NO_x sensor, follow the steps listed below:

1. Prepare the machine for maintenance. Refer to Operation and Maintenance Manual, "Prepare the Machine for Maintenance".

2. Remove the covers to gain access to the sensors.
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   Illustration 1	g06375856

3. Disconnect harness assembly and disconnect sensor cabling (1).

4. Remove NO_x sensor probe (2).
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   Illustration 2	g03495917

5. Install inlet NO_x sensor probe. Take precautions to prevent damaging the ceramic sensor element (3) when installing.

6. Ensure that the sensor is securely mounted.

7. Connect harness assembly and cabling.

   Note: Ensure that the NO_x sensor is not covered with insulation. The insulation would trap heat in the sensor body and cable. This heat may cause sensor failure.

8. Install cover plate assemblies and bolts. Refer to Specifications, SENR3130, "Torque Specifications" for the proper torque.