Kubota P0113 – Engine Control Module (ECM / Engine ECU): Intake Air Temperature (IAT) Sensor 1 Circuit High Input

The sensor operates using a thermistor where resistance decreases as air temperature rises. If the circuit is open or shorted to the battery, the sensor outputs a voltage of 4.9V or more for 2.8 seconds or longer. The ECU interprets this abnormally high voltage as an unrealistically cold intake air temperature (often defaulting to -40°C/-40°F), which disrupts the engine's air-fuel mixture calculations.

• V3800
• V3307
• V2403
• V2607
• V1505
• D1803
• C3.3B
• M108X
• SSV65
• SSV75
• SVL75-2
• SVL95-2
• KX080-3
• KX121-3
• U15-3
• U17-3
• U35-3
• U45-3
• U55-4

1. 1

   Verify battery voltage is normal before proceeding with diagnostics

2. 2

   Use a diagnostic scanner to read the live IAT value (an extreme negative temperature like -40°F strongly points to an open circuit)

3. 3

   Visually inspect the IAT sensor for unplugged connectors, broken wires, or corroded pins

4. 4

   Backprobe the sensor connector to verify that the 5V reference voltage and ground are present from the ECU

5. 5

   Measure the internal resistance of the IAT sensor and compare it to Kubota's OEM specifications for the current ambient temperature

1. 1

   Turn the ignition key to the OFF position and disconnect the battery to prevent electrical shorts.

2. 2

   If the diagnostic checks revealed a loose or corroded connector, clean the terminals with electrical contact cleaner, ensure the pins are straight, and securely reconnect the harness.

3. 3

   If the wiring harness is damaged (causing an open circuit or short to +B), repair or replace the affected section of the wiring harness.

4. 4

   If the IAT sensor failed the resistance test, unclip the wiring harness and remove the faulty sensor from the intake air tract.

5. 5

   Install the new OEM Intake Air Temperature sensor and secure it in place.

6. 6

   Reconnect the electrical connector, ensuring it clicks into place.

7. 7

   Reconnect the battery, turn the key on, and use an OBD/J1939 scan tool to clear the P0113 fault code.

8. 8

   Start the engine and monitor live data to ensure the IAT sensor is now reading the correct ambient air temperature and the code does not return.