Kubota P1173 – Engine Control Module (ECM): EPR/CFV comm lost

The Engine Control Module (ECM) stops receiving CAN communication packets from the EPR/CFV unit for more than 500 milliseconds while the engine is running, causing the ECM to illuminate the MIL, disable adaptive learning, and initiate a Power Derate 2 condition.

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

1. 1

   Check for related codes (DTC 1174, 1175, 1177) to rule out power supply issues or internal EPR failure

2. 2

   Inspect the wiring harness between the ECM and the EPR/CFV for open circuits, shorts to ground, or physical damage

3. 3

   Verify that the CAN terminals at the EPR/CFV connector are fully seated, free of corrosion, and not backed out

4. 4

   Measure the supply voltage at the EPR/CFV connector (must be between 18.0 VDC and 33.0 VDC)

1. 1

   Power Down

   Turn the ignition key to the OFF position and disconnect the negative battery cable.

2. 2

   Inspect and Clean

   Disconnect the electrical pigtail at the EPR/CFV unit. Clean the contacts with electronic contact cleaner and ensure the pins are straight.

3. 3

   Test Harness Continuity

   Using a multimeter, check the continuity of the CAN High and CAN Low wires from the EPR/CFV connector back to the 90-pin ECM connector. Repair any breaks in the wiring.

4. 4

   Replace the EPR/CFV

   If the wiring harness, power, and ground are all within specification, the EPR/CFV unit has failed internally and must be replaced. Relieve any residual fuel line pressure, disconnect the fuel inlet and outlet hoses from the EPR/CFV, unbolt the regulator assembly from its mounting bracket, install the new EPR/CFV, reconnect the fuel lines, and plug in the electrical connector.

5. 5

   Clear Codes

   Reconnect the battery, turn the key ON, and use the E-Controls GCP (diagnostic laptop tool) to clear the fault codes.

6. 6

   Test Run

   Start the engine and verify that it runs smoothly without triggering the MIL or entering a derated power state.