Case IH 3902 – EDC (Electronic Diesel Control) / Engine ECU: NOx Sensor (CAN): NOx Sensor temperature out of range

The engine control system is receiving a temperature reading from the Nitrogen Oxide (NOx) sensor via the Controller Area Network (CAN) bus that falls outside of the expected operational parameters. This typically points to a failure of the sensor's internal heater, a damaged sensor probe, or a wiring issue preventing accurate temperature reporting.

• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 225
• Magnum 235
• Magnum 260
• Magnum 290
• Magnum 315
• Magnum 340
• Magnum 370
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Quadtrac 450
• Quadtrac 500
• Quadtrac 550
• Quadtrac 600
• Farmall 110A
• Farmall 120A
• Farmall 130A
• Farmall 140A
• Farmall 115U
• Combine 5130
• Combine 6130
• Combine 7130
• Combine 7230
• Combine 8230
• Combine 9230
• Titan 3030
• Titan 3530
• Titan 4030
• Titan 4530
• Sprayer 2240
• Sprayer 4430
• Loader 521F
• Loader 621F
• Loader 721F
• Loader 821F
• Loader 921F
• Loader 1021F
• Loader 1121F

1. 1

   Scan for Accompanying Codes: Check the EDC for other related SCR/NOx codes (such as 3521, 3528, 3529, 3530, 3532, or 3533) which confirm a hard sensor failure or CAN timeout.

2. 2

   Visual Inspection: Inspect the NOx sensor wiring harness and the 5-pin MCON connector for melting, chafing, corrosion, or loose pins.

3. 3

   Exhaust Leak Check: Check the exhaust system for leaks upstream of the sensor, which can skew temperature readings and trigger plausibility faults.

4. 4

   Clear and Retest: Clear the code using a diagnostic tool to see if it is a hard fault (returns immediately) or an intermittent issue.

1. 1

   Turn off the machine and disconnect the battery

   Turn off the machine and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the faulty NOx sensor

   Locate the faulty NOx sensor on the exhaust system (typically located downstream, behind the catalytic converter).

3. 3

   Disconnect the electrical connector

   Disconnect the 5-pin electrical connector from the machine's wiring harness.

4. 4

   Unscrew the NOx sensor

   Carefully unscrew the NOx sensor from the exhaust pipe using a specialized sensor socket or wrench. (Penetrating oil may be needed if the sensor is seized in the exhaust).

5. 5

   Install the new NOx sensor

   Install the new NOx sensor into the exhaust pipe. Ensure the threads have high-temperature anti-seize compound (often pre-applied to new OEM sensors). Tighten to the manufacturer's specified torque.

6. 6

   Route the sensor wire and reconnect

   Route the sensor wire safely away from extreme heat sources and reconnect the 5-pin plug.

7. 7

   Reconnect the battery

   Reconnect the battery.

8. 8

   Clear the fault code

   Connect a diagnostic tool to clear the 3902 fault code. An error cleaning/reset is required after fitting a new NOx sensor so the ECU recognizes the new component and resets the SCR system adaptations.