Cummins Fault Code
Free · no signup559 (SPN 157 FMI 18)
Engine bogs under load; Hard starting; Misfire; Sudden shutdown.
System
Not specified
Symptom
Engine bogs under load; Hard starting; Misfire; Sudden shutdown.
Diagnosis & fix steps
Fuel Rail Pressure Low - Data Valid but Below Normal.
LOGIC: Actual rail pressure is significantly lower than commanded pressure.
ACTION: 1. Change Fuel Filters.
2. Check Suction Control Valve (SCV).
3. Perform Injector Leak-Back test.
FIX: Replace Fuel Filters (90% of cases); replace Pressure Relief Valve or Pump.
Red Seal field insights
Never chase this code until you have replaced both fuel filters. A slightly restricted filter is the most common cause of a 559 code.
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