Cummins Fault Code
Free · no signupSPN 157 FMI 1
Hard starting; Engine stalling under load; Misfiring; Severe power loss.
System
Not specified
Symptom
Hard starting; Engine stalling under load; Misfiring; Severe power loss.
Diagnosis & fix steps
Fuel Rail Pressure Low
LOGIC: Pressure lower than commanded (Leak or Restriction).
ACTION: Check filters for restriction. Inspect high-pressure lines for leaks. Perform pump "click test" via software.
FIX: Replace Fuel Filters. If persists, replace Fuel Relief Valve or High-Pressure Pump.
Red Seal field insights
90% of the time, this is just a dirty fuel filter. Always swap both filters before touching the expensive pump.
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