Question 1

What does Komatsu fault code 168-4 mean?

Accepted Answer

168-4 (Electrical): Controller "Brown Out" Fix: LOGIC: Battery Potential / System Voltage Low.

ACTION: Load test batteries and inspect the main battery relay (disconnect) for pitted contacts.

Question 2

What does Komatsu fault code 989L00 mean?

Accepted Answer

989L00 (Security): No start; Controller Lock Caution. Fix: Controller Lock Caution.

LOGIC: Security lockout (Mode 1).

ACTION: Sync monitor and ECM.

FIX: Enter Service Menu and re-sync password.

Question 3

What does Komatsu fault code A001 / Event 16 mean?

Accepted Answer

A001 / Event 16 (Electric Propulsion): No Propulsion / DC Bus Warning Lamp Fix: LOGIC: Main Inverter DC Bus Undervoltage / Link Discharge Incomplete.

ACTION: Inspect main alternator phase excitation diodes and rectifier bridge. Measure DC bus link discharge resistor circuit continuity and verify capacitor bank balance with a high-voltage insulation tester.

Question 4

What does Komatsu fault code A105 / Code 105 mean?

Accepted Answer

A105 / Code 105 (Electric Propulsion): Propulsion Cut / Inverter Fault Code Fix: LOGIC: Grid Chopper Resistor Over-Temperature Circuit Tripped.

ACTION: Check thermal switch continuity on the retarder resistor grid banks. Blow metallic dust out of grid insulators and inspect grid cooling blower motor operation.

Question 5

What does Komatsu fault code AA10NX mean?

Accepted Answer

AA10NX (Intake): Engine Derate (E11); Air filter light. Fix: Air Cleaner Clogging.

LOGIC: Intake vacuum switch triggered by restriction.

ACTION: Inspect filters.

FIX: Replace both Air Filters.

Question 6

What does Komatsu fault code CA2249 / P228C mean?

Accepted Answer

CA2249 / P228C (Fuel System): Derate / Engine Stumble Fix: LOGIC: Common Rail Fuel Pressure Too Low (Regulator Limit Reached).

ACTION: Check fuel lift pump delivery pressure. Inspect the high-pressure fuel rail relief valve for excessive return-line leakage (bypassing fuel back to tank).

Question 7

What does Komatsu fault code CA559 mean?

Accepted Answer

CA559 (Fuel System): Derate / Engine Stalls Fix: 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.

Question 8

What does Komatsu fault code CA559 mean?

Accepted Answer

CA559 (Fuel System): Derate / Engine Stalls under Load Fix: 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.

Question 9

What does Komatsu fault code CA559 / SPN 157 FMI 18 mean?

Accepted Answer

CA559 / SPN 157 FMI 18 (Fuel System): Power Cut under Load / Stalling Fix: LOGIC: High Pressure Common Rail (HPCR) Fuel Pressure Below Threshold.

ACTION: Check primary fuel filter/water separator for restriction or air aeration. Test high-pressure pump relief valve for bypass leakage.

Question 10

What does Komatsu fault code Code 2301 / A2301 mean?

Accepted Answer

Code 2301 / A2301 (Safety / Interlock): Hoist Body Inoperative / Dump Locked Fix: LOGIC: Hoist Lever Position Sensor 1 & 2 Correlation Fault.

ACTION: Measure dual Hall-effect sensor signal sweeps on the cab hoist control lever. Recalibrate hoist lever neutral, raise, float, and lower end-points via monitor panel.

Code	System	Symptom	Full fix
168-4	Electrical	Controller "Brown Out"	View fix
989L00	Security	No start; Controller Lock Caution.	View fix
A001 / Event 16	Electric Propulsion	No Propulsion / DC Bus Warning Lamp	View fix
A105 / Code 105	Electric Propulsion	Propulsion Cut / Inverter Fault Code	View fix
AA10NX	Intake	Engine Derate (E11); Air filter light.	View fix
CA2249 / P228C	Fuel System	Derate / Engine Stumble	View fix
CA559	Fuel System	Derate / Engine Stalls	View fix
CA559	Fuel System	Derate / Engine Stalls under Load	View fix
CA559 / SPN 157 FMI 18	Fuel System	Power Cut under Load / Stalling	View fix
Code 2301 / A2301	Safety / Interlock	Hoist Body Inoperative / Dump Locked	View fix
Code 52-11	Electric Propulsion	Propulsion Cutout / Blower Warning	View fix
DHPAMA	Hydraulic Monitoring	Hydraulic Drift / Error Code Active	View fix
DX19KZ	Hydraulic	Travel Motor Shift Malfunction / Active E03 Alarm	View fix
DXE5KA	Hydraulic System	Slow Attachment Movement / No Pump Merge	View fix
E012 / CA2384	Hydraulics	Swing Function Soft / Heavy Machine Lug	View fix
E02	—	Pump Contol Error.	View fix
E042 / SPN 100 FMI 1	Lubrication	Automatic Level 3 Engine Shutdown	View fix
E11	—	Engine Derate. Significant loss of power; "Engine Protection" active.	View fix
E15	Hydraulics	Loss of Power. Engine stalls when the operator moves the joysticks.	View fix
E15 / CA428	Hydraulics / Engine	Engine Surging / RPM Fluctuation	View fix
E15 / CA428	Hydraulics / Engine	Engine Surging / RPM Fluctuation	View fix
E15 / CA428	Hydraulics / Engine	Engine Surging / RPM Fluctuation	View fix
E202	Hydraulic	LS Select Solenoid Valve: Short Circuit	View fix
Event 200 / F-02	Electric Propulsion	Dynamic Retarding Dead / Overheat Alert	View fix
Event 311 / E311	Electric Propulsion	Propulsion Cut / Retard Grid Alarm	View fix
P0562	Electrical	Controller Comm. Lost	View fix
SPN 3509 FMI 3	Electrical	All Digging Telemetry Lost on Dash	View fix
SPN 3509 FMI 4	Electrical	All Digging Telemetry Lost on Monitor	View fix
SPN 520201 FMI 05	Hydraulics	Boom Up Drift / Slow Raise Cycle	View fix
SPN 520285 FMI 14	Hydraulics	Ripper Stalls / Low Penetration Force	View fix
SPN 702 FMI 3	Electrical / Controls	Attachment Hydraulics Dead	View fix

Komatsu Fault Codes

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