John Deere 94.03 – Engine Control Unit (ECU): Low Pressure Fuel Sensor Voltage Too High

The signal voltage from the low-pressure fuel sensor (or fuel rail pressure sensor) is higher than the expected normal range. This condition is typically caused by a short to power (12 volts) in the sensor wiring harness, an open circuit, a faulty connector, or an internal failure of the fuel pressure sensor itself.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 7420
• 7520
• 7710
• 7810
• 8120
• 9230
• 9330
• 9430
• 9530
• 9630
• 750J
• 850J
• 444J
• 544J
• 624J
• 310K
• 310SL
• 410L
• 710K
• 250D
• 370E
• 410E
• S540
• S670
• S770

1. 1

   Inspect the wiring harness leading to the low-pressure fuel sensor for chafing, bare wires, or pinched sections that could cause a short to power

2. 2

   Disconnect the sensor and check the pins for corrosion, moisture, or poor terminal tension

3. 3

   Use a multimeter to check the sensor signal circuit for a short to 12V or an open circuit

4. 4

   Verify via a diagnostic tool (like Service ADVISOR) that the barometric pressure sensor is reading accurately, as a fault there can skew fuel pressure calculations

5. 5

   Install a mechanical pressure gauge in-line with the output of the low-pressure fuel pump to verify actual fuel pressure against the sensor's electronic readings

1. 1

   Turn off the engine, remove the key, and relieve any residual pressure in the fuel system before disconnecting lines or sensors.

   Relieve residual pressure

2. 2

   If the diagnostic checks reveal damaged wiring or a short to power in the harness, repair or replace the affected wiring harness section (e.g., Remote Low Pressure Fuel Sensor Wiring Harness).

   Repair or replace wiring harness

3. 3

   If the wiring and connectors test good, the fault lies within the sensor itself. Disconnect the electrical connector from the fuel pressure sensor.

   Disconnect sensor connector

4. 4

   Unthread and remove the faulty fuel pressure sensor from the fuel rail or filter housing.

   Remove faulty sensor

5. 5

   Install the new OEM replacement sensor and tighten to the manufacturer's specified torque.

   Install new sensor

6. 6

   Reconnect the electrical harness.

   Reconnect harness

7. 7

   Turn the key on, clear the 000094.03 / SPN 94 FMI 3 fault code from the ECU using a diagnostic tool, and start the engine to verify the code does not return and that fuel pressure reads normally.

   Clear code and verify