New Holland 3529 – ECU: NOx Sensor Failure – Open Load

The Engine Control Unit (ECU) has detected an electrical open circuit in the NOx (Nitrogen Oxide) sensor system. An open load condition signifies a break in the electrical circuit, which can be caused by a disconnected or damaged wire, a faulty connector, or an internal failure within the NOx sensor itself. This failure prevents the ECU from receiving accurate NOx readings, which are required to properly manage the Selective Catalytic Reduction (SCR) system and reduce harmful emissions.

• T7.220
• T7.235
• T7.250
• T7.260
• T7.270
• T8 Series
• Powerstar 90
• Powerstar 100
• Powerstar 110
• Powerstar 120
• T4.90
• T4.100
• T4.110
• T4.120
• T5.90
• T5.100
• T5.110
• T5.120
• T6.120
• T6.140
• T6.150
• T6.155
• B110C
• B110CTC
• B95C
• B95CLR
• B95CTC
• C238
• D125C
• D150C
• D180C

1. 1

   Visually inspect the entire wiring harness leading to the NOx sensor for signs of physical damage, such as chafing, melting from contact with hot exhaust components, or corrosion.

2. 2

   Disconnect the NOx sensor and inspect the connector pins for corrosion, moisture, or damage. Ensure pins are making a solid connection and are not pushed back into the housing.

3. 3

   Using a multimeter, check for continuity on the signal and power supply wires between the ECU and the NOx sensor connector. A resistance reading greater than 0.5 Ω may indicate a wiring fault.

4. 4

   With the key on, verify that the NOx sensor is receiving the correct voltage at its connector according to manufacturer specifications.

5. 5

   Use a diagnostic scanner to check for any other active or stored fault codes related to the after-treatment system (e.g., exhaust temperature sensors or AdBlue dosing system), as these can sometimes trigger related NOx sensor codes.

1. 1

   Allow exhaust to cool

   Ensure the exhaust system is cool to the touch to prevent burns and damage to the new sensor.

2. 2

   Disconnect faulty sensor

   Disconnect the electrical connector from the NOx sensor module.

3. 3

   Remove old sensor

   Using the appropriate size wrench, carefully unscrew the NOx sensor from the exhaust pipe.

4. 4

   Prepare for installation

   If the new sensor does not come with anti-seize compound on the threads, apply a small amount of a suitable ceramic anti-seize to the threads. Be careful not to get any on the sensor tip.

5. 5

   Install new sensor

   Screw the new NOx sensor into the exhaust pipe and tighten it to the manufacturer's specified torque.

6. 6

   Connect new sensor

   Securely connect the electrical connector to the new NOx sensor module.

7. 7

   Clear codes and reset

   Use a diagnostic tool to clear the 3529 fault code. Perform any required reset or adaptation procedures to ensure the ECU recognizes the new component.

8. 8

   Test drive and verify

   Operate the machine under various conditions to allow the ECU to relearn and confirm that the fault does not reappear.