If your Komatsu excavator is showing an error code on the monitor panel, accurate diagnosis is the first step toward a reliable repair. Whether you operate a PC-7 series (mechanical engine), PC-8 series (common rail), or the PC-8MO model, this comprehensive guide covers all user codes, service codes, and diagnostic troubleshooting tables.
At Engine Replacement Parts, we supply OEM-grade components—from IMV valves and injectors to sensors, solenoids, and engine controllers—to get your machine back to work. Use this guide to identify the fault, then let us provide the parts you need.
Part 1: Komatsu PC-7 Series Fault Codes
These models use the HYPER system with mechanical engine control. Codes are divided into User Codes (auto display), Service Codes, and diagnostic tables.
User Codes (Auto Display)
| Code | System |
|---|
| E01 | HYPER System – Auto Mode |
| E02 | PC-EPC System |
| E03 | Swing Parking Brake System |
| E04 + CALL | HYPER System – Joystick Neutral System |
| E05 | Governor Motor System |
| E06 + CALL | HYPER System – EPC Solenoid Drive System |
| E09 | HYPER-GX System Shutdown |
| CALL | HYPER Joystick / EPC Solenoid Drive System |
Service Codes (Switch-Operated)
| Code | Description |
|---|
| E101 | Abnormal fault history record |
| E102 | Clock data abnormal |
| E103 | Buzzer output short circuit |
| E104 | Air cleaner clogged |
| E108 | Coolant temperature above 105°C |
| E112 | Wiper motor forward drive short circuit |
| E113 | Wiper motor reverse drive short circuit |
| E114 | Washer drive circuit short circuit |
| E115 | Wiper movement abnormal |
| E116 | Wiper retraction abnormal |
| E117 | Engine controller S-net communication failure |
| E118 | Pump control S-net communication failure |
| E128 | Monitor communication abnormal |
| E201 | Travel interlock solenoid short circuit |
| E202 | LS select solenoid circuit short |
| E203 | Swing holding brake solenoid short |
| E204 | Merging/dividing solenoid short |
| E205 | 2-stage relief solenoid short |
| E206 | Travel speed solenoid short |
| E207 | Quick mode solenoid short |
| E208 | Quick mode solenoid open |
| E211 | Travel interlock solenoid open |
| E213 | Swing holding brake solenoid open |
| E214 | Merging/dividing solenoid open |
| E215 | 2-stage relief solenoid open |
| E216 | Travel speed solenoid open |
| E217 | Input mode code abnormal |
| E218 | S-network communication break |
| E222 | LS-EPC solenoid short |
| E223 | LS-EPC solenoid open |
| E224 | Front pump pressure sensor abnormal |
| E225 | Rear pump pressure sensor abnormal |
| E226 | Pressure sensor power supply abnormal |
| E227 | Engine speed sensor abnormal |
| E232 | PC-EPC solenoid short |
| E233 | PC-EPC solenoid open |
| E247 | Arm retract PPC pressure sensor abnormal |
| E248 | Bucket curl PPC pressure sensor abnormal |
| E257 | Pump abnormal |
| E315 | Battery relay drive short |
| E91B | Engine Ne speed sensor issue |
| E91C | Engine G speed sensor issue |
| E920 | Engine type selection error |
| E921 | Engine type mismatch |
| E931 | Fuel dial system error |
| E934 | Engine coolant high temperature sensor error |
| E936 | Engine oil pressure switch error |
| E93C | Engine boost sensor error |
| E93D | Engine fuel temperature sensor error |
| E953 | Engine communication abnormal |
| E954 | Engine start switch short |
| E955 | Engine S-net error |
| E956/E957 | Engine power supply failure |
| E970/E971 | PCV1/PCV2 current overload |
| E974/E975 | PCV1/PCV2 circuit cut |
| E977 | Rail pressure sensor error |
| E979/E97A/E97B/E97C/E97D | Rail pressure related faults |
| E980 | Engine controller abnormal |
| E981–E986 | Fuel injector #1–#6 open circuit |
| E98A/E98B | Fuel injector short circuit |
| AA10NX | Air cleaner clogged |
| AB00KE | Charging voltage low |
| B@BAZG | Engine oil pressure low |
| B@BAZK | Engine oil level low |
| B@BCNS | Engine coolant overheating |
| B@BCZK | Radiator coolant level low |
| B@HANS | Hydraulic oil overheating |
PC-7 Series Diagnostic Tables (E/H/S Modes)
These diagnostic modes help isolate electrical, hydraulic, and engine issues.
E Mode – Electrical System Troubleshooting
| Code | Description |
|---|
| E-1 | Engine does not start (engine does not turn) |
| E-2 | Preheater does not work |
| E-3 | Automatic warm-up does not work |
| E-4 | Auto decelerator does not work |
| E-5 | All attachments, swing, travel do not move |
| E-6 | One-touch power boost switch does not work |
| E-7 | Machine thrust increase function abnormal |
| E-9 | Monitor panel completely blank |
| E-18 | Windshield wiper does not work |
| E-19 | Buzzer alarm cannot be canceled |
H Mode – Hydraulic & Mechanical System Troubleshooting
| Code | Description |
|---|
| H-1 | All attachments underpowered or slow travel/swing |
| H-2 | Engine speed suddenly drops or engine stalls |
| H-3 | Attachments, travel or swing do not move |
| H-4 | Abnormal noise from hydraulic pump |
| H-5 | Auto decelerator does not work |
| H-7 | Boom moves slow or underpowered |
| H-8 | Arm moves slow or underpowered |
| H-9 | Bucket moves slow or underpowered |
| H-19 | Machine veers during travel |
| H-24 | Machine does not swing |
| H-25 | Poor swing acceleration or slow swing |
| H-26 | Excessive overrun when swing stops |
S Mode – Engine System Troubleshooting
| Code | Description |
|---|
| S-1 | Poor starting performance |
| S-2 | Engine does not start |
| S-3 | Engine does not accelerate smoothly |
| S-4 | Engine stalls during operation |
| S-5 | Engine runs rough (vibration) |
| S-6 | Engine lack of power |
| S-7 | Black exhaust (incomplete combustion) |
| S-8 | Excessive oil consumption (blue smoke) |
| S-12 | Engine oil pressure warning light on |
| S-14 | Water temperature too high (overheat) |
Part 2: Komatsu PC-8 Series Fault Codes
The PC-8 series uses a common rail fuel system with advanced electronics. Codes include user codes, CA series (engine), and D series (hydraulic/pump).
User Codes
| Code | System |
|---|
| E02 | PC-EPC System |
| E03 | Swing Parking Brake System |
| E10 | Engine controller power supply failure (engine stops) |
| E11 | Engine control system failure (power reduced) |
| E14 | Feedback system abnormality |
| E15 | Engine sensor fault (coolant, fuel pressure, oil pressure) |
| EOE | Network communication failure |
Engine Control Codes (CA Series)
| Code | Fault Description |
|---|
| CA111 | ECM critical internal fault |
| CA115 | Engine speed sensor & backup sensor failure |
| CA122/CA123 | Intake pressure sensor high/low |
| CA131/CA132 | Throttle sensor high/low |
| CA144/CA145 | Coolant temperature sensor high/low |
| CA153/CA154 | Intake temperature sensor high/low |
| CA155 | Intake temperature high speed drop |
| CA187/CA227 | Sensor power supply voltage low/high |
| CA221/CA222 | Atmospheric pressure sensor high/low |
| CA234 | Engine overspeed |
| CA238 | Ne speed sensor power supply voltage fault |
| CA271/CA272 | IMV/PCV1 short/open – Common rail fuel control |
| CA322–CA332 | Injector #1–#6 open/short circuit |
| CA342 | Calibration code incompatible |
| CA351 | Injector drive circuit fault |
| CA352/CA386 | Sensor power supply voltage low/high |
| CA428/CA429 | Fuel water separator sensor high/low |
| CA435 | Engine oil pressure switch fault |
| CA441/CA442 | Battery voltage low/high |
| CA449/CA451/CA452 | Rail pressure extremely high / sensor high/low |
| CA488 | Intake temperature high (torque reduced) |
| CA553/CA559 | Rail pressure high/low |
| CA689 | Engine Ne speed sensor fault |
| CA731 | Engine backup speed sensor phase fault |
| CA757 | All continuous data lost |
| CA778 | Engine backup speed sensor fault |
| CA2185/CA2186 | Throttle sensor power supply high/low |
| CA2249 | Rail pressure extremely low |
| CA2311 | IMV solenoid coil fault |
| CA2555/CA2556 | Grid heater relay voltage high/low |
Hydraulic & Pump Codes (D Series)
| Code | Fault Description |
|---|
| D19JKZ | Personnel code relay abnormal |
| D862KA | GPS antenna open circuit |
| DA22KK | Pump solenoid coil power supply low |
| DA25KP | 5V sensor 1 power supply abnormal |
| DA29KQ | Model selection abnormal |
| DA2RMC | CAN break (pump controller) |
| DGH2KB | Hydraulic oil temperature sensor short |
| DHPAMA/DHPBMA | Front/Rear pump pressure sensor abnormal |
| DHS3MA | Arm retract PPC pressure sensor abnormal |
| DHS4MA | Bucket curl PPC pressure sensor abnormal |
| DHS8MA | Boom raise PPC pressure sensor abnormal |
| DHSAMA/DHsbMA | Right/Left swing PPC pressure sensor abnormal |
| DHSDMA | Bucket dump PPC pressure sensor abnormal |
| DHX1MA | Overload sensor abnormal |
| DW43KA/DW43KB | Travel speed solenoid open/short |
| DW45KA/DW45KB | Swing brake solenoid open/short |
| DW91KA/DW91KB | Travel merging solenoid open/short |
| DWK0KA/DWK0KB | 2-stage relief solenoid open/short |
| DXA8KA/DXA8KB | PC-EPC (front pump) open/short |
| DXA9KA/DXA9KB | PC-EPC (rear pump) open/short |
| DXE0KA/DXE0KB | LS-EPC solenoid open/short |
| DXE5KA/DXE5KB | Main merging/dividing solenoid open/short |
| DY20KA/DY20MA | Wiper operation / parking abnormal |
| DY2CKA/DY2CKB | Washer drive open/short |
Part 3: Komatsu PC-8MO Series Additional Codes
The PC-8MO models include enhanced electronic features and additional fault codes for air conditioning, CAN bus, and sensors.
| Code | Description |
|---|
| 879AKA/879AKB | A/C internal sensor open/short |
| 879BKA/879BKB | A/C external sensor open/short |
| 879CKA/879CKB | Ventilation sensor open/short |
| 879DKZ | Sunlight sensor open/short |
| 879EMC/879FMC | Ventilation/air mix damper abnormal |
| 879GKX | Refrigerant abnormal |
| D110KB | Battery relay drive short |
| D811MC | KOMTRAX error |
| D8AQKR | CAN2 break (KOMTRAX) |
| DA26KP | 5V sensor 2 power supply abnormal |
| DA2QKR | CAN2 break (pump controller) |
| DAF0MB/DAF0MC | Monitor memory/fault |
| DAF8KB | Camera power short |
| DAFGMC | Positioning module fault |
| DAZ9KQ/DAZQKR | AC model selection / CAN2 break (AC ECU) |
| DB2QKR | CAN2 break (engine control) |
| DHA4KA | Air cleaner clogged sensor open |
| DHS9MA | Boom lower PPC pressure sensor abnormal |
| DHSCMA | Arm extend PPC pressure sensor abnormal |
| DHSFMA–DHSJMA | Left/Right travel forward/reverse PPC sensors |
| DR21KX/DR31KX | Camera reverse drive abnormal |
| DV20KB | Travel alarm short |
| DWK2KA/DWK2KB | Variable back pressure solenoid open/short |
| DXE4KA/DXE4KB | Attachment flow EPC open/short |
PC-8/8MO Electrical (E Mode), Hydraulic (H Mode) & Engine (S Mode) Diagnostic Tables
These extended diagnostic modes help isolate modern electronic and hydraulic issues.
E Mode – Electrical System (Partial List)
| Code | Description |
|---|
| E-1 | Engine does not start (engine does not turn) |
| E-2 | Preheater does not work |
| E-4 | Basic check monitor lights up with engine stopped |
| E-5 | Caution monitor lights up with engine running |
| E-6 | Emergency stop monitor lights up with engine running |
| E-7 | Fuel gauge display incorrect |
| E-14 | Auto decelerator does not work |
| E-20 | Attachments, swing, travel do not move or cannot be locked |
| E-21 | Swing lock brake does not work |
| E-23 | Travel alarm does not sound or sounds continuously |
| E-25 | Windshield wiper and washer do not work |
| E-36 | KOMTRAX system does not work |
H Mode – Hydraulic & Mechanical System
| Code | Description |
|---|
| H-1 | Low speed or power for all attachments, swing, travel |
| H-2 | Engine speed drops sharply or engine stalls |
| H-3 | Attachments, swing, travel do not work |
| H-4 | Abnormal noise around hydraulic pump |
| H-6 | Boom speed or power low |
| H-7 | Arm speed or power low |
| H-8 | Bucket speed or power low |
| H-17 | Machine does not travel straight |
| H-18 | Travel speed slow |
| H-22 | Upper structure does not swing |
| H-23 | Poor swing acceleration or slow swing speed |
| H-24 | Excessive overrun when swing stops |
S Mode – Engine System
| Code | Description |
|---|
| S-1 | Poor starting performance |
| S-2 | Engine does not start |
| S-3 | Engine does not accelerate smoothly |
| S-4 | Engine stops during operation |
| S-5 | Engine runs rough / unstable |
| S-6 | Engine lack of power |
| S-7 | Black exhaust (incomplete combustion) |
| S-8 | Excessive oil consumption (blue smoke) |
| S-12 | Engine oil pressure drops |
| S-14 | Coolant temperature too high (overheat) |
| S-15 | Abnormal noise |
Common Failure Patterns & Recommended Parts
| Symptoms | Likely Code | Recommended Replacement Part |
|---|
| Engine stalls, surges, or won’t start | CA271, CA272, CA2311 | IMV (Inlet Metering Valve) |
| Poor acceleration, low power | E11, CA449, CA2249 | IMV, Fuel Supply Pump, or Rail Pressure Sensor |
| Machine moves slowly or lacks power | E02, DXA8/DXA9, DXE0 | PC-EPC or LS-EPC Solenoid |
| Engine speed unstable (PC-7) | E05, E316, E317, E318 | Governor Motor or Speed Sensor |
| Injector circuit codes | CA322–CA332, E981–E986 | Fuel Injector(s) |
| Air cleaner clogged | E104, AA10NX | Air Filter Element |
| Hydraulic overheating | B@HANS | Hydraulic Oil Cooler / Fan System |
Pro Troubleshooting Tips
- Verify the series: PC-7 and PC-8 codes are not interchangeable.
- Check battery voltage first: Many CA codes (CA441, CA442, CA187) are caused by low or unstable electrical power.
- Inspect wiring harnesses: Corroded or chafed wires often cause solenoid and sensor codes.
- Use OEM-grade replacements: Aftermarket sensors and solenoids can lead to recurring faults.
- Use diagnostic modes (E/H/S): These structured tables help narrow down root causes faster than random part swapping.
Need Help Diagnosing or Finding a Part?
At Engine Replacement Parts, we stock a wide range of genuine and OEM-grade components for Komatsu excavators—including IMV valves, injectors, PC-EPC solenoids, governor motors, sensors, and complete engine assemblies. Provide your machine model and fault code, and we’ll help you find the right replacement.
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