Cummins Fault Code
Free · no signupCummins 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.
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