Case IH 3138 – Engine Control Unit (ENG / EDC): Metering unit - temperature too high

This code indicates that the Engine Control Unit has detected an abnormally high temperature or an out-of-range electrical condition (often related to the power stage) at the fuel metering unit (also known as the Fuel Control Actuator, MPROP, or Suction Control Valve).

• Magnum 235
• Magnum 245
• Magnum 275
• Magnum 305
• Magnum 310
• Magnum 335
• Magnum 340
• Puma 140
• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Steiger 330
• Steiger 485
• Steiger 535
• Farmall 115U
• MX215
• MX245
• MX275
• MX305

1. 1

   Check the wiring harness and connectors between the Engine ECU and the fuel metering unit for shorts, opens, or high resistance

2. 2

   Verify the ECU power stage output to the metering unit to ensure it is sending the correct pulse-width modulated (PWM) signal without voltage drops

3. 3

   Test the fuel metering unit itself for internal electrical faults or physical overheating

4. 4

   Check the high-pressure fuel system components, specifically verifying if the Rail Pressure Sensor is providing inaccurate readings or if the High-Pressure Fuel Pump is defective

1. 1

   Safety First

   Turn off the machine, remove the key, and allow the engine and high-pressure fuel system to cool down.

2. 2

   Inspect the Harness

   Locate the fuel metering unit on the high-pressure fuel pump. Disconnect the electrical connector and inspect the pins for corrosion, melting, or pushed-back terminals.

3. 3

   Test the Circuit

   Using a multimeter, check the continuity of the wiring from the metering unit connector back to the Engine ECU. Repair any damaged wiring.

4. 4

   Test the Rail Pressure Sensor

   Monitor the fuel rail pressure sensor via a diagnostic scan tool. If the sensor is reading inaccurately (e.g., showing low pressure when actual pressure is high), it will command the metering unit to stay open, causing it to overheat. Replace the rail pressure sensor if readings are erratic.

5. 5

   Replace the Metering Unit

   If the wiring and rail pressure sensor are good, the fuel metering unit's internal solenoid is likely failing. Remove the mounting bolts securing the metering unit to the high-pressure pump, remove the old unit, lubricate the O-rings on the new unit with clean diesel fuel, and install the new unit.

6. 6

   Clear Codes

   Reconnect all harnesses, turn the key to the ON position, and use a diagnostic tool to clear fault code 3138. Start the engine and verify that the code does not return under load.