Kubota P1112 – Engine Control Module (ECM): RPM Above Spark Rev Limit Level

This fault code indicates an engine overspeed condition. It triggers when the engine speed exceeds the maximum allowed spark rev limit for longer than 1 second. When this code is set, the system will illuminate the Malfunction Indicator Lamp (MIL) and disable the spark to protect the engine.

• WG1605
• WG1605-G-E3
• WG1605-L-E3
• WG1605-GL-E3
• WG1903
• WG2503
• WG3800

1. 1

   Verify operating conditions to determine if an actual engine overspeed event occurred (e.g., operator error, steep incline, or mechanical failure).

2. 2

   Inspect the Crankshaft Position Sensor (CKP) and the coded trigger wheel on the flywheel for faults or erratic input.

3. 3

   Check the wiring harness between the CKP sensor and the 90-pin ECM connector for chafing, shorts to voltage, or shorts to ground.

4. 4

   Check for electrical noise or irregular crank patterns causing crank re-synchronization events.

1. 1

   Address Mechanical Overspeed

   If the operator confirms the engine physically oversped, correct the underlying mechanical or operational issue. Clear the code and test run the machine.

2. 2

   Inspect Sensor and Connector

   If no actual overspeed occurred, locate the Crankshaft Position Sensor on the engine block adjacent to the flywheel. Disconnect the sensor and inspect the pins for corrosion, moisture, or damage.

3. 3

   Test the Circuit

   Using a multimeter, verify continuity of the CKP signal wires from the sensor connector back to the ECM. Ensure there is no short to ground or short to power in the harness.

4. 4

   Replace the Sensor

   If the wiring harness tests good and the connector is clean, the Crankshaft Position Sensor has likely failed internally and is sending erratic RPM spikes to the ECM. Replace the sensor.

5. 5

   Clear and Verify

   Reconnect all components, clear the P1112 DTC using a diagnostic scan tool, and run the engine under load to verify the code does not return.