What does Cummins fault code 559 (SPN 157 FMI 18) mean?

Q: What does Cummins fault code 559 (SPN 157 FMI 18) mean?

559 (SPN 157 FMI 18) indicates: Engine bogs under load; Hard starting; Misfire; Sudden shutdown. Fix: 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.

Cummins Fault Code

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559 (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.

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.

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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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