Exhaust Gas NOx Sensor: Service and Repair

Nitrogen Oxides (NOx) Sensor













Removal

NOTICE: Do not use silicone based sprays or lubricants on any components installed onto or around the diesel exhaust system or intake air distribution and filtering system. Silicone reacts with the Nitrogen Oxides (NOx) sensor and may cause permanent damage to the NOx sensor.

NOTE: If the Nitrogen Oxides (NOx) sensor function is suspect, replace the sensor, do not attempt to clean the sensor.

1. NOTICE: Make sure the ignition switch is in the OFF position prior to working on the electronic engine controls or the vehicle may be damaged.

Turn the ignition switch to the OFF position.

2. NOTE: If the Nitrogen Oxides (NOx) sensor wiring protective sheath is damaged, inspect the wires. If there are any abrasions or cuts on the wires, replace the sensor.

NOTE: Any melting of plastic connectors indicates overheating of the Diesel Particulate Filter (DPF). Address any DPF concerns before installing a new sensor.

Disconnect the NOx sensor electrical connector.

3. NOTE: The NOx sensor wiring harness routing and position of retainers varies by wheel base. Typical application shown in graphic.

Note the location of the wiring harness retainers for installation.

- Detach the wiring harness retainers.





4. NOTE: If necessary, lubricate the NOx sensor with penetrating and lock lubricant to ease removal.

Remove the Nitrogen Oxides (NOx) sensor.

Installation

1. NOTE: Check for the presence of anti-seize on the first 3 threads of the sensor. If there is no anti-seize present or is partially missing, apply anti-seize to the first 3 threads of the Nitrogen Oxides (NOx) sensor prior to installation.

Install the NOx sensor.

- Tighten to 50 Nm (37 lb-ft).

2. NOTE: The NOx sensor wiring harness routing and position of retainers varies by wheel base. Typical application shown in graphic.

Attach the wiring harness retainers as noted during removal.





3. NOTE: Do not apply any type of electrical grease or lubricants to the electrical connector.

Connect the NOx sensor electrical connector.