Kubota P1111 – Engine Control Module (ECM): RPM Above Fuel Rev Limit Level

This code indicates an engine overspeed condition where the engine RPM has exceeded the maximum allowable limit for fuel delivery. It is typically triggered by either a genuine mechanical overspeed event or a faulty crankshaft position sensor (or its input circuit) sending erroneously high or erratic RPM signals to the computer. When this code is set, the system's safety action is to disable the spark and fuel to protect the engine from damage.

• Kubota WG1605
• Kubota WG1903
• Kubota WG2503
• Kubota WG3800

1. 1

   Interview the operator to determine if the fault occurred during a specific load condition (e.g., a sudden drop in hydraulic load or traveling down a steep incline) which could have caused a genuine mechanical overspeed

2. 2

   Connect a diagnostic scanner (such as the Kubota Gasoline Service Tool - KGST) and monitor the live engine RPM data for erratic spikes that do not match the actual engine speed

3. 3

   Inspect the governor operation and throttle control to ensure the accelerator is not sticking and the throttle body is functioning correctly

4. 4

   Inspect the wiring harness leading to the crankshaft position sensor for shorts to ground, shorts to voltage, or loose connector terminals that could cause signal noise

1. 1

   Safety First

   Turn off the equipment, engage the parking brake, and disconnect the negative battery terminal.

2. 2

   Locate the Sensor

   Locate the crankshaft position sensor, which is installed on the engine block near the flywheel side.

3. 3

   Disconnect and Inspect

   Unplug the sensor's electrical connector. Check the pins for corrosion, moisture, or damage.

4. 4

   Remove the Sensor

   If the wiring is intact but diagnostic checks showed erratic RPM signals (or the sensor is confirmed dead), remove the retaining bolt holding the crankshaft position sensor and pull the sensor out of the block.

5. 5

   Install the New Part

   Insert the replacement crankshaft position sensor and tighten the retaining bolt to the OEM torque specification.

6. 6

   Reconnect

   Plug the electrical connector back into the sensor until it clicks securely.

7. 7

   Clear Codes

   Reconnect the battery. Turn the ignition to the Key-On, Engine-Off position. Use your diagnostic tool to clear the P1111 / SPN 515 fault code.

8. 8

   Test Run

   Start the engine and monitor the RPMs. Ensure the engine idles smoothly, the governor responds correctly under load, and the fault code does not return.