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.
Same code keeps coming back?
That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.
Read before you touch anything
- This is general reference information, not a repair manual. It is for trained, qualified technicians.
- Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
- Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
- You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
- Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.
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