Kubota P1175 – Engine Control Module (ECM): EPR/CFV Voltage Supply Low

The Engine Control Module (ECM) has detected that the supply voltage to the Electronic Pressure Regulator (EPR) or Continuous Flow Valve (CFV) has dropped below the acceptable operating threshold.

• WG1605
• WG1605-G-E3
• WG1605-L-E3
• WG1605-GL-E3
• WG2503
• WG3800
• LiuGong CLG2020H/C2
• Hyundai
• Skyjack
• Snorkel
• Vermeer
• PowerBoss
• Zamboni

1. 1

   System Voltage Check: Verify the machine's battery and alternator/charging system are outputting the correct voltage.

2. 2

   Wiring Harness Inspection: Inspect the wiring harness connecting the ECM to the EPR/CFV for open circuits, shorts to ground, chafed wires, or heat damage.

3. 3

   Connector Pin Check: Disconnect the EPR/CFV connector and the ECM header. Check for pushed-out pins, corrosion, or moisture.

4. 4

   Voltage Drop Test: Using a digital multimeter (DMM), measure the supply voltage directly at the EPR/CFV connector to confirm if the voltage is actually low at the component.

5. 5

   CAN Bus Check: Ensure the CAN terminal connections are secure, as the EPR communicates with the ECM via the CAN network.

1. 1

   Connect Diagnostic Tool

   Connect the E-Controls GCP (laptop diagnostic tool) or equivalent Kubota scan tool to verify P1175 is the only active code. If communication codes (like P1173) are also present, address the CAN network first.

2. 2

   Test the Power Circuit

   With the key ON, probe the power supply wire at the EPR/CFV connector.

3. 3

   Repair Wiring/Relays

   If the voltage at the connector is significantly lower than battery voltage, trace the circuit back to the ECM or power relay. Repair any damaged wiring, clean ground connections, or replace a faulty power relay causing the voltage drop.

4. 4

   Replace the EPR/CFV

   If the wiring harness, relays, and ECM supply voltage test perfectly fine, but the code remains active, the internal circuitry of the EPR/CFV actuator is likely shorting out and pulling the voltage down. Replace the EPR/CFV unit.

5. 5

   Clear and Verify

   Clear the fault code using the diagnostic tool. Run the engine under load to ensure the code does not return and the engine no longer derates.