New Holland ENG 3519 – Engine Control Unit (ECU / EDC): Ambient Air Temperature Sensor failure (of Humidity Sensor) - CAN Signal failure

The engine control system has lost communication with the combined humidity and ambient air temperature sensor over the CAN (Controller Area Network) bus. The sensor is either failing to broadcast its data, or there is an open/short in the CAN communication lines preventing the signal from reaching the controller.

• T8.xxx Series
• T9 Series
• T9.700
• CR6090
• CR9090
• CX8080 Elevation
• CX8090 Elevation
• Magnum 235-340 (Series 4)
• Optum 300CVT

1. 1

   Inspect the wiring harness and the connector at the humidity/ambient air temperature sensor for physical damage, corrosion, moisture ingress, or pushed-out pins.

2. 2

   Verify that the sensor is receiving its required 5V DC reference supply and has a solid ground.

3. 3

   Test the CAN High and CAN Low communication lines between the sensor connector and the Engine ECU. Check for continuity and ensure the CAN network resistance is correct (typically 60 ohms across the network when powered down).

4. 4

   Look for codes ENG 3517 (Signal too high) or ENG 3518 (Signal too low). If these are present alongside 3519, it heavily points to a wiring short or a completely failed sensor element.

1. 1

   Power Down

   Turn off the machine, remove the key, and engage the battery master disconnect switch to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the humidity/ambient air temperature sensor, which is typically mounted on the engine air intake ducting/housing.

3. 3

   Disconnect

   Depress the locking tab and carefully unplug the electrical pigtail from the sensor.

4. 4

   Remove

   Remove the mounting hardware (screws or twist-lock mechanism) securing the sensor to the intake and pull the faulty sensor out.

5. 5

   Install

   Insert the new replacement sensor into the intake housing and secure it with the mounting hardware.

6. 6

   Reconnect

   Plug the electrical connector back in, ensuring it clicks and locks into place.

7. 7

   Clear Codes

   Turn the battery disconnect switch back on, turn the ignition key to the ON position, and use the CNH Electronic Service Tool (EST) or the in-cab diagnostic display to clear the inactive ENG 3519 fault code. Run the engine to verify the code does not return.