New Holland ENG 3105 – ENGINE: Rail Pressure Relief Valve - Pressure Shock Requested

When the Engine Control Unit (ECU) detects that the rail pressure is too high and the Pressure Relief Valve (PRV) has not opened naturally, the ECU intervenes by requesting a 'pressure shock' (a sudden, intentional spike in pressure) to force the PRV open and relieve the system.

• T4 series
• T4.65
• T4.115
• T5 series
• T5.95
• T5.105
• T5.115
• T5000
• T6000
• T7000
• T8 series
• T9 series
• L316
• L318
• L320
• L225
• L230
• C232
• C238
• CR9090
• CX8080
• CX8090

1. 1

   Check the fuel metering unit (M-PROP/FCA) wiring harness for short circuits to the battery or ground (often accompanied by codes 3107 or 3108).

2. 2

   Verify the rail pressure sensor is reading accurately and check its wiring continuity to the ECU.

3. 3

   Test the low-pressure fuel system to ensure supply pressures between the fuel filter and the inlet to the high-pressure pump are at a minimum of 5 bar (72 psi). Vacuum between the low-pressure pump inlet and the tank should not exceed 5 inches of Hg.

4. 4

   Run the engine while observing fuel pressure and looking for air in the fuel. Perform a 'wiggle test' on each fuel line and sensor harness to check for loose connections.

1. 1

   Depressurize the System

   Turn off the machine, disconnect the battery, and allow the engine to sit so the extreme high pressure in the common rail can dissipate.

2. 2

   Clean the Area

   Clean the fuel rail and surrounding components thoroughly. Installation requires extreme cleanliness, as even microscopic contamination can destroy common rail components.

3. 3

   Remove the PRV

   Locate the Pressure Relief Valve on the common fuel rail. Disconnect the fuel return line attached to it, then unthread the valve from the rail.

4. 4

   Install the New PRV

   Thread the new precision-engineered relief valve into the rail and torque it to the OEM specification. Reattach the fuel return line.

5. 5

   Address the Root Cause

   Replace the fuel metering unit on the high-pressure pump if it was diagnosed as the cause of the initial overpressure event.

6. 6

   Filter Replacement & Priming

   Replace the primary and secondary fuel filters. Always use fresh, filtered fuel when priming the system to prevent introducing new contaminants.

7. 7

   Clear Codes

   Reconnect the battery, use a diagnostic tool to clear the ENG 3105 (and any related) fault codes, and run the machine to verify that rail pressure remains within normal operating limits.