New Holland NH 3037 – Engine Controller (Engine ECU / EDC): Power stage Fuel filter heater - SOURCE HIGH

This code indicates that the control module has detected a 'Source High' condition on the power stage circuit for the fuel filter heater, which typically means the circuit voltage is higher than expected, pointing to a short circuit to battery voltage (B+) or an open circuit on the power supply side of the fuel filter heater element or its relay circuit.

• T5.95
• T5.105
• T5.115
• T6
• T7
• T8
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• E215B
• E245B

1. 1

   Inspect the wiring harness running from the Engine ECU to the fuel filter heater relay and the heater element for chafed wires, melted insulation, or pinched wires that could cause a short to battery voltage

2. 2

   Test the fuel filter heater relay in the fuse/relay box for internal shorts, or swap it with a known good relay of the same type

3. 3

   Disconnect the fuel filter heater element and the relay, then check the signal wire from the ECU to the relay and the power wire from the relay to the heater for any unintended voltage (short to B+)

4. 4

   Disconnect the connector at the fuel filter heater and measure the resistance (Ohms) across the heater element pins to check if it has failed internally (completely open or dead shorted)

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the Components

   Locate the fuel filter housing (usually mounted on the side of the engine block or chassis) and the main electrical distribution box where the heater relay is housed.

3. 3

   Repair Wiring

   If the diagnostic checks revealed a short to voltage in the harness, repair the damaged section of the wire using proper soldering and heat-shrink tubing, or replace the affected harness section.

4. 4

   Replace the Relay

   If the relay is stuck closed or internally shorted, pull the old relay and install a new OEM replacement.

5. 5

   Replace the Heater Element

   Drain a small amount of fuel from the filter housing if necessary. Unplug the electrical connector from the fuel filter heater. Unscrew the heater element from the fuel filter housing (or replace the entire filter bowl/housing if the heater is integrated and non-removable). Install the new heater element and torque to OEM specifications. Reconnect the electrical plug.

6. 6

   Prime and Clear

   Reconnect the battery. Turn the key to the ON position to prime the fuel system. Use a diagnostic scan tool to clear the NH 3037 fault code from the Engine ECU. Start the engine and verify the code does not return.