New Holland 3517 – ECU: Ambient Air Temperature Sensor Signal Too High

The Engine Control Unit (ECU) has detected a voltage signal from the ambient air temperature sensor (humidity sensor) that is higher than the expected range. This typically indicates an open circuit in the sensor's ground wire, a short circuit to power in the signal wire, or an internal failure of the sensor itself. This fault may affect the system's ability to accurately monitor environmental conditions, which the ECU relies on for engine performance and emissions control calculations.

• T7 Series
• T8 Series
• TG Series
• T8010
• T8020
• T8030
• T8040
• T8050
• TG215
• TG245
• TG275
• TG305
• CR Series Combines
• CR9040
• CR9060
• CR9065
• CX Series
• MX Series
• STX Series
• T9 Series
• T8000 Series
• Steiger Series
• T6000 Series
• T7000 Series

1. 1

   Visually inspect the ambient air temperature sensor and its wiring harness for any signs of damage, corrosion, or loose connections. The sensor is often located near the front grille or radiator, or sometimes along the frame rail of the machine.

2. 2

   Check for 'Ghost' Codes: Ensure the battery is fully charged and all primary power and ground connections to the chassis are clean and tight to rule out erroneous fault codes caused by low battery voltage.

3. 3

   Disconnect the sensor and inspect the connector terminals for corrosion, moisture, or damage. Check the wiring harness for any chafing, breaks, or short circuits between the sensor and the ECU.

4. 4

   Perform a sensor resistance test using a multimeter set to Ohms (Ω). Disconnect the sensor, connect leads to the two pins, and gently warm the sensor with a heat gun or hairdryer. The resistance should decrease as temperature rises. If the reading is open, shorted, or does not change, the sensor is likely faulty.

1. 1

   Disconnect power

   Turn off the machine and disconnect the battery to prevent any electrical damage during the repair.

2. 2

   Remove the faulty sensor

   Locate the ambient air temperature sensor (typically held in place by a plastic clip or a single bolt). Disconnect the electrical harness and remove the sensor.

3. 3

   Install the new sensor

   Install the replacement sensor in the mounting location and securely connect the electrical harness.

4. 4

   Reconnect power and clear codes

   Reconnect the battery. On many New Holland machines, the fault code will clear itself once the underlying issue is resolved. If the code persists, it may need to be cleared using the CNH EST software or by a qualified technician.

5. 5

   Verify the repair

   Start the machine and let it run. Use a diagnostic tool to monitor the ambient air temperature reading to confirm the new sensor is functioning correctly and the fault code does not reappear.