Case IH 19574 – VCM or ECM: Open circuit error for the NOx signal

The control module has detected a break or loss of continuity (an open circuit) in the signal wire communicating with the Nitrogen Oxide (NOx) sensor.

• Tier 4b
• Magnum (180, 200, 220, 240, 250, 280, 310, 340)
• Puma (150, 150 CVT, 165, 165 CVT)
• Farmall (110A, 120A, 130A, 140A)
• Combines (5140, 6140, 7140, 7240, 8240, 9240)
• Patriot (2250, 3240, 3340, 4440)
• Titan (3040, 3540, 4040, 4540)
• Case N-Series TLBs

1. 1

   Scan for accompanying codes using a professional diagnostic tool to determine if the fault is for the Inlet (Pre-SCR) or Outlet (Post-SCR) NOx sensor.

2. 2

   Inspect the NOx sensor wiring harness and the 5-pin connector for physical damage, melted wires, soot build-up, or moisture intrusion.

3. 3

   Turn the ignition key to the ON position (engine off) and test the power supply voltage at the sensor harness connector (target voltage is typically between 16V and 36V).

4. 4

   Check the signal wire for continuity between the sensor connector and the ECM/VCM to rule out a broken wire in the main harness.

5. 5

   Note that NOx sensors do not become fully operational until the exhaust reaches operating temperature and is free of moisture.

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 aftertreatment pipe (either upstream or downstream of the SCR catalyst, depending on which sensor the scan tool flagged).

3. 3

   Disconnect the electrical connector

   Disconnect the 5-pin electrical connector from the sensor module.

4. 4

   Unscrew the NOx sensor probe

   Carefully unscrew the NOx sensor probe from the exhaust pipe. Note: These can be seized due to heat; penetrating oil may be required.

5. 5

   Install the new NOx sensor

   Install the new NOx sensor into the exhaust pipe and tighten to OEM torque specifications.

6. 6

   Route the sensor wiring and reconnect

   Route the sensor wiring away from extreme heat sources and reconnect the 5-pin connector.

7. 7

   Reconnect battery and clear codes

   Reconnect the battery, connect your diagnostic tool, and clear the fault codes.

8. 8

   Verify repair

   Run the machine until the exhaust reaches operating temperature to verify the sensor initializes and the code does not return.