Case IH 3529 (DTC E16E) - ECU – Engine Control Unit (ECU) or Dosing Control Unit (DCU): Downstream NOx sensor internal failure (Heater Open Circuit Error)

The electrical path for the internal heating element of the downstream NOx sensor is broken (open load). This is almost always caused by a burnt-out heating element inside the sensor itself, though it can occasionally be caused by a severed wire in the sensor's pigtail harness.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Combines 5130, 6130, 7130, 7230, 8230
• Magnum series (180 through 370)
• Steiger series (350 through 600)
• Quadtrac (450-600)
• Farmall series (110A, 120A, 130A, 140A, 115U)
• Titan 2240, 3030, 3530, 4030, 4530
• Case Wheel Loaders (521F, 621F, 721F, 821F, 921F, 1021F, 1121F)

1. 1

   Inspect the wiring harness and connector leading to the downstream NOx sensor (located on the exhaust tailpipe, after the SCR catalyst) for chafed wires, melted insulation, or disconnected pins.

2. 2

   Check the machine's fuse box for any blown fuses related to the emissions system or engine sensor heating circuits.

3. 3

   Check for other active SCR/DEF fault codes (such as 3530 for a short circuit, or 3533 for a CAN timeout). If 3529 is the only code present, the sensor itself has likely failed internally.

1. 1

   Power Down

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

2. 2

   Locate the Sensor

   Locate the downstream NOx sensor on the exhaust system. It will be positioned downstream of the SCR catalyst/DPF.

3. 3

   Disconnect

   Unplug the electrical connector for the NOx sensor from the main wiring harness.

4. 4

   Removal

   Carefully unscrew the NOx sensor from the exhaust bung. Note: Penetrating oil and a specialized O2/NOx sensor socket may be required to prevent stripping the hex head.

5. 5

   Installation

   Apply a small amount of high-temp anti-seize compound to the threads of the new sensor (if not already pre-applied). Be extremely careful not to get any anti-seize on the sensor probe itself, as this will ruin the sensor.

6. 6

   Torque

   Thread the new NOx sensor into the exhaust bung and tighten to the manufacturer's torque specification.

7. 7

   Reconnect

   Reconnect the electrical connector and ensure the wiring harness is secured away from hot exhaust components.

8. 8

   Clear Codes

   Reconnect the battery. Connect a diagnostic tool to clear the fault codes. Error cleaning is required after fitting a new NOx sensor to extinguish the SCR warning light and reset the system.