Kubota P0604 – Engine Control Unit (ECU): Microprocessor Failure - RAM

The internal RAM check performed by the control module has failed, corrupted, or returned an implausible value, which typically forces a Power Derate 2 or an Engine Stop (Fuel Cut).

• WG972-E4
• V2403-CR-TE4
• L3301
• L3560
• L3901
• L4060
• L47
• L4701
• L4760
• L5060
• L5460
• L6060
• M62
• MX4800
• MX5200
• MX5800
• DC68
• DC70
• ERH450
• Haulotte HA16RTJ
• Haulotte HA26 RTJ Pro

1. 1

   Ensure the battery voltage is correct and the ECU is receiving proper power and ground, as severe voltage drops can sometimes cause memory check anomalies.

2. 2

   Clear the diagnostic trouble codes (DTCs) using a Kubota diagnostic tool.

3. 3

   Cycle the key (Key On, Engine Off) and attempt to start the engine to see if the code returns.

4. 4

   Check if the ECU is at the latest calibration level; in some rare instances, a module reprogramming/update may resolve a corrupted RAM issue.

1. 1

   Disconnect battery

   Disconnect the negative battery cable.

2. 2

   Disconnect ECU

   Locate the Engine ECU on the machine and carefully disconnect the wiring harness connectors.

3. 3

   Remove ECU

   Unbolt and remove the faulty ECU.

4. 4

   Replace or repair ECU

   Install a brand-new OEM replacement ECU (which will likely need to be programmed/flashed by a Kubota dealer) or send the faulty ECU to a specialized heavy-equipment module repair service.

5. 5

   Reinstall ECU

   Reinstall the repaired or new ECU, reconnect the harnesses, and reconnect the battery.

6. 6

   Clear codes and test

   Clear any residual codes and test run the machine.