Kubota P0072 – Engine ECU: Intake air temperature built-in MAF sensor abnormality: Low

The Engine ECU detects that the voltage signal from the intake air temperature sensor (integrated into the Mass Air Flow sensor) has dropped to 0.1 V or less for 2.8 seconds or more, indicating a ground short circuit in the sensor or wiring harness, or a complete internal failure of the sensor.

• V1803
• V2403
• V2607
• V3307
• V3800
• KX040-4
• KX057-4
• KX080-4
• U48-5
• U55-4
• SSV65
• SSV75
• SVL65-2
• SVL75-2
• SVL90-2
• SVL95-2S
• SVL97-2
• L3301
• L3901
• L4701
• L6060
• M6060
• M7060

1. 1

   Verify the machine's battery voltage is normal, as low system voltage can skew sensor readings.

2. 2

   Inspect the wiring harness and the 5-pin connector at the MAF sensor for corrosion, backed-out pins, or chafed wires that could cause a short to ground.

3. 3

   Check the voltage at the Engine ECU terminals to ensure the ECU is outputting the correct 5V reference signal to the sensor.

4. 4

   Disconnect the MAF sensor and measure the resistance between the intake air temperature terminals on the sensor itself to determine if the internal thermistor has failed.

5. 5

   Use a diagnostic tool to monitor the live voltage of the 'Intake air temp built-in MAF sensor.' If it reads 0.1 V or less continuously despite good wiring, the sensor is faulty.

1. 1

   Disconnect battery

   Turn off the machine and disconnect the negative battery terminal.

2. 2

   Locate MAF sensor

   Locate the Mass Air Flow (MAF) sensor, which is installed on the air intake tract downstream from the air filter housing.

3. 3

   Disconnect connector

   Disconnect the 5-pin electrical connector from the MAF sensor.

4. 4

   Repair wiring

   If diagnostic tests proved a wiring short to ground, trace the harness back to the Engine ECU and repair the damaged wire.

5. 5

   Remove faulty sensor

   If the wiring is intact and the sensor failed the resistance/voltage checks, remove the mounting screws securing the MAF sensor to the intake pipe and pull the sensor out.

6. 6

   Install new sensor

   Install the new MAF sensor, ensuring the O-ring/seal is seated properly to prevent unmetered air leaks.

7. 7

   Reinstall hardware

   Reinstall the mounting screws and reconnect the 5-pin electrical connector.

8. 8

   Verify repair

   Reconnect the battery, clear the P0072 fault code using a diagnostic scan tool, and run the engine to verify the code does not return and that DPF regeneration is no longer inhibited.