Cummins Fault Code

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Cummins 118 (SPN 157 FMI 3)

Loud engine knock; Severe power loss (Limp Mode); Check Engine Light.

System

Not specified

Symptom

Loud engine knock; Severe power loss (Limp Mode); Check Engine Light.

Diagnosis & fix steps

Rail Pressure Voltage High. LOGIC: Signal > 4.5V (Open Circuit). ACTION: Jumper Signal to Return; if code becomes 117, harness is good. Check for 5V ref. FIX: Replace Rail Pressure Sensor or repair broken wire in harness.

Red Seal field insights

This sensor and the Boost sensor often share the same 5V supply. If you have codes for both at the same time, look for a single wire break near the ECM where the supply line splits.

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.

Book an uptime review

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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