Komatsu Fault Code
Free · no signupCA559
Derate / Engine Stalls
Variant 1
System
Fuel System
Symptom
Derate / Engine Stalls
Diagnosis & fix steps
LOGIC: High Pressure Common Rail (HPCR) Fuel Pressure Below Threshold.
ACTION: Check primary fuel filter/water separator for restriction or aeration. Test high-pressure pump relief valve for bypass leakage.
Red Seal field insights
Root Cause: Extremely common in harsh environments due to fuel contamination, clogged filters, or worn lift pumps starving the HPCR.
Variant 2
System
Fuel System
Symptom
Derate / Engine Stalls under Load
Diagnosis & fix steps
LOGIC: High Pressure Common Rail (HPCR) Fuel Pressure Below Threshold.
ACTION: Check primary fuel filter/water separator for restriction or aeration. Test high-pressure pump relief valve for bypass leakage.
Red Seal field insights
Root Cause: Extremely common in harsh environments due to fuel contamination, clogged filters, or worn lift pumps starving the HPCR.
Track this across your whole fleet
This code is free to read. AM Fleet Integrity lets your team log fault codes against assets, plus the full fault-code library, QR operator reporting, PM scheduling and predictive alerts. Start free — no credit card required.
Start your free trial