Massey Ferguson E171.03 – Engine ECU: Ambient Temperature Sensor Voltage Issue

The signal voltage from the ambient air temperature sensor is exceeding the expected normal range, typically caused by an open circuit in the sensor wiring, a disconnected sensor, a short to a power source, or an internally failed sensor.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Visually inspect the ambient temperature sensor and its 2-pin oval connector for corrosion, moisture, or backed-out pins

2. 2

   Check the wiring harness for an open circuit (broken wire) or a short to a voltage source between the sensor and the ECU

3. 3

   Disconnect the sensor and measure its resistance with a multimeter (an infinite resistance reading indicates the NTC thermistor has failed internally)

4. 4

   With the key ON and the sensor disconnected, check the connector for the 5V reference signal from the ECU

1. 1

   Turn off the tractor ignition and disconnect the negative battery terminal to prevent electrical spikes.

   Ensure the tractor is completely powered down before beginning electrical work.

2. 2

   Locate the ambient air temperature sensor.

   Typically mounted near the front grille, air intake path, or exterior cab depending on the exact model.

3. 3

   Depress the locking tab on the 2-pin oval electrical connector and pull it free from the sensor.

   Disconnect the wiring harness from the sensor.

4. 4

   Remove the faulty sensor.

   These are typically pressed into a mounting bracket or secured with a simple retaining clip.

5. 5

   Press the new OEM replacement sensor into the mounting location.

   Ensure the sensor is securely seated in its bracket or clip.

6. 6

   Reconnect the electrical harness, ensuring it clicks securely into place.

   Verify the 2-pin oval connector is fully engaged.

7. 7

   Reconnect the battery.

   Restore power to the tractor.

8. 8

   Turn the ignition ON and use a diagnostic scan tool to clear the E171.03 fault code from the Engine ECU.

   Start the tractor and verify the code does not return.