Case IH 547 – Engine Controller (ENG / ECM): Fuel Pressure sensor voltage is too low.

This is an electrical circuit code indicating that the Engine Control Module (ECM) is receiving a voltage signal from the fuel rail pressure sensor that falls below the acceptable minimum threshold. This typically points to a short to ground in the sensor wiring, an open circuit in the 5V reference supply line, a disconnected harness, or a complete internal failure of the sensor itself.

• MX Magnum
• STX Steiger
• Magnum
• Steiger
• Maxxum
• Farmall
• Axial-Flow

1. 1

   Inspect the fuel pressure sensor connector and the wiring harness leading to the Engine ECU for chafed wires, corrosion, moisture, or backed-out pins.

2. 2

   With the key ON and engine OFF, disconnect the sensor and use a multimeter to verify that the sensor is receiving the proper 5V reference voltage and has a solid ground from the ECM.

3. 3

   Check for continuity on the signal wire between the sensor connector and the Engine ECU to rule out a broken wire (open circuit).

4. 4

   Take an ohm reading across the sensor pins (e.g., between pins 1 and 2, and pins 1 and 3). If the internal resistance is out of specification (e.g., showing a dead short), the sensor has failed internally.

5. 5

   Ensure there are no severe fuel restrictions (like heavily clogged fuel filters) causing erratic pressure readings.

1. 1

   Preparation

   Turn off the machine, remove the key, and disconnect the battery master switch to prevent electrical shorts and depressurize the fuel system.

2. 2

   Locate the Sensor

   Locate the fuel pressure sensor, which is threaded directly into the high-pressure fuel rail.

3. 3

   Clean the Area

   Thoroughly clean the fuel rail and the area around the base of the sensor. Crucial step: The high-pressure fuel system is highly sensitive to contamination; no dirt can be allowed to enter the open rail.

4. 4

   Disconnect

   Unplug the electrical harness connector from the sensor.

5. 5

   Remove

   Use a deep socket or wrench to carefully unscrew the faulty sensor from the fuel rail.

6. 6

   Install

   Thread the new OEM fuel pressure sensor into the rail by hand to prevent cross-threading, then tighten it to the manufacturer's specified torque.

7. 7

   Reconnect

   Plug the electrical harness back into the sensor, ensuring the locking tab clicks into place.

8. 8

   Clear Codes & Test

   Reconnect the battery. Use a diagnostic tool (such as Case IH EST or Jaltest) to clear the ENG 547 fault code. Prime the fuel system if necessary, start the engine, check for fuel leaks at the sensor threads, and verify the code does not return.