Detroit Diesel Fault Code
Free · no signupSPN 520268 FMI 18
Engine Derate / Extended Crank
System
Fuel System
Symptom
Engine Derate / Extended Crank
Diagnosis & fix steps
LOGIC: Low Pressure Fuel System Pressure Below Minimum Limit.
ACTION: Perform low-pressure fuel system pressure and aeration test using fuel diagnostic gauge set. Check fuel lift pump and filter cap seals.
Red Seal field insights
Aeration & Supply: Air pulled into low-pressure fuel gallery starves high-pressure pump plungers, causing low rail pressure delivery.
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