Case IH F-5571-15 - ECU – Engine Control Unit (ECU): Fuel pressure relief valve reached maximum allowed opening count.

The mechanical Pressure Relief Valve (PRV), which is integral to the common fuel rail, is designed to open and bleed off fuel into the return line if excessive rail pressure occurs to protect the injectors and fuel system. The Engine Control Unit (ECU) monitors sudden drops in rail pressure and counts each time the PRV is forced open. If this internal counter exceeds the maximum allowed threshold (typically 50 openings), the ECU triggers this fault code.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Austoft 9900 sugarcane harvesters
• Magnum
• MX
• Farmall series
• Case loaders (570NXT, SR250, SV300)

1. 1

   Check for related active faults in the diagnostic menu, specifically fuel pump pressure limits (3141 / DTC 4465), fuel rail pressure limits (3309 / DTC 1865), fuel metering unit failures (3137 / DTC 5255, 3910 / DTC 4155), or rail pressure deviation limits (3293, 3301)

2. 2

   Diagnose and repair any related active faults first, as a faulty fuel metering unit or rail pressure sensor is likely causing the pressure spikes forcing the PRV open

3. 3

   If no other faults are active, inspect the PRV for tightness, internal leaks, and verify its opening pressure

1. 1

   Resolve related faults

   Resolve any active fuel metering unit or rail pressure sensor faults as outlined above.

2. 2

   Remove old PRV

   If the PRV is determined to be the root cause (or if the counter has maxed out without an active overpressure condition), safely relieve the fuel system pressure and remove the old Pressure Relief Valve from the fuel rail.

3. 3

   Install new PRV

   Install the new PRV and torque it to the manufacturer's specifications.

4. 4

   Reset PRV counter

   CRITICAL STEP: You must use the Case IH Electronic Service Tool (EST) laptop software to perform a "PRV counter reset" (Reset of the working cycles of the fuel pressure relief valve). If you do not reset this routine control service counter in the ECU, the fault code will remain active even with a new valve installed.

5. 5

   Verify repair and check ECU software

   Return the machine to service and run the engine to verify the fault does not return. If the fault remains active after a reset, check the ECU for the appropriate software version and re-flash if necessary.