Kubota P0108 – Engine Control Module (ECM) / Engine Control Unit (ECU): Manifold Absolute Pressure/Barometric Pressure Circuit High Input

The control module detects that the voltage signal from the MAP sensor is abnormally high (typically exceeding 4.5V to 4.9V) for a set duration, indicating a higher-than-expected pressure or lack of vacuum that does not correlate with engine speed and throttle position. This is usually caused by a short to power in the wiring, a failed sensor, or a severe vacuum leak.

• WG1605
• WG1603
• WG2503
• RTV500
• RTV400
• LS300GK

1. 1

   Visually inspect the MAP sensor wiring harness and connector for corrosion, loose pins, or damaged wires that could cause a short to power.

2. 2

   Connect an OBD2 scanner and monitor the 'Intake Air Pressure Sensor' live data. Check if the voltage fluctuates based on engine load or if it is stuck near 5V.

3. 3

   Test the three wires at the MAP sensor connector with a multimeter: verify the 5-volt reference wire, the ground wire, and the signal wire output. If the reference and ground are good but the signal is stuck high, the sensor is likely internally shorted.

4. 4

   Inspect for mechanical issues such as disconnected vacuum hoses, severe intake air leaks, or a clogged air filter/exhaust.

1. 1

   Locate the Sensor

   Find the MAP sensor (often a combined TMAP sensor measuring temperature and pressure) located directly on the intake manifold.

2. 2

   Disconnect Battery

   Disconnect the negative battery cable to protect the ECM.

3. 3

   Remove the Sensor

   Unplug the electrical connector from the MAP sensor. Remove the retaining screws or bolts holding the sensor to the manifold.

4. 4

   Inspect the Port

   Pull the old sensor out and inspect the intake port for heavy carbon buildup or debris. Clean if necessary.

5. 5

   Install the New Sensor

   Ensure the rubber O-ring on the new MAP sensor is intact and lightly lubricated so it seats properly without tearing (a torn O-ring will cause a vacuum leak). Secure it with the retaining screws.

6. 6

   Reconnect

   Plug the electrical connector back in and reconnect the battery.

7. 7

   Clear Codes

   Use a diagnostic scan tool to clear the P0108 fault code from the ECM memory.

8. 8

   Test Drive

   Start the engine, check for a smooth idle, and verify that the check engine light does not return.