Kubota P0073 – Engine ECU: Intake air temp. built-in MAF sensor: High

The Engine Control Unit (ECU) is receiving an abnormally high voltage signal (4.9 Volts or more for 2.8 seconds or longer) from the intake air temperature sensor, which is integrated into the Mass Air Flow (MAF) sensor assembly. This condition is almost always caused by an open circuit or a short circuit to the battery voltage (+B) in the sensor itself or the wiring harness.

• D1803
• V1803
• V2403
• V2607
• V3307
• V3800
• KX040-4
• KX057-4
• KX080-4
• U48-5
• U55-4
• U55-5
• SSV65
• SSV75
• SVL65-2
• SVL75-2
• SVL90-2
• SVL95-2S
• SVL97-2
• L3301
• L3901
• L4701
• L6060
• M-Series (M5, M6)
• LX-Series

1. 1

   Verify Battery Voltage: The ECU requires normal battery voltage to accurately run the diagnostic logic for this sensor.

2. 2

   Visual Inspection: Locate the MAF sensor on the air cleaner housing or intake pipe. Inspect the 5-pin electrical connector and the wiring harness for corrosion, water intrusion, melted plastic, or broken wires.

3. 3

   Check for Open/Short Circuits: Use a multimeter to test the wiring harness between the MAF sensor connector and the Engine ECU. Look for a broken wire (open circuit) or a wire that is shorted to a 12V power source.

4. 4

   Live Data / Voltage Test: Using a diagnostic scan tool, check the live data for the Intake Air Temperature voltage. If it is pegged at 4.9V or 5.0V, unplug the sensor. If the voltage drops, the sensor is internally shorted/open and must be replaced. If the voltage remains high while unplugged, the wiring harness is shorted to power.

1. 1

   Turn off the machine's key switch and disconnect the negative battery cable

   This prevents electrical spikes during the repair.

2. 2

   Locate the MAF sensor assembly

   Find the sensor on the engine's air intake pipe/air cleaner assembly.

3. 3

   Disconnect the 5-pin electrical connector

   Depress the locking tab and disconnect the connector from the MAF sensor.

4. 4

   Repair wiring harness if damaged

   If harness damage was found during diagnostics, repair the broken or shorted wires and replace the connector pigtail if the pins are corroded.

5. 5

   Remove the mounting screws

   If the sensor itself failed, remove the mounting screws securing the MAF sensor to the intake housing.

6. 6

   Remove the old MAF sensor

   Pull the old MAF sensor straight out of the housing.

7. 7

   Insert the new MAF sensor

   Ensure the O-ring seals properly against the intake pipe to prevent unmetered air leaks.

8. 8

   Secure the sensor

   Secure the sensor with the mounting screws.

9. 9

   Reconnect the 5-pin electrical connector

   Push the connector until it clicks into place.

10. 10

    Reconnect the negative battery cable

    Restore power to the machine.

11. 11

    Clear fault code and verify repair

    Turn the key to the ON position and use a diagnostic scan tool to clear the P0073 fault code. Start the engine and verify that the code does not return and that the intake air temperature reads accurately.