The Komatsu PC400 is a heavy-duty hydraulic excavator designed for demanding earthmoving and construction applications. Its instrument cluster provides operators with essential, model-specific alerts to ensure safe and efficient operation. Understanding these indicators is critical for avoiding downtime and preventing component damage.
Komatsu PC400 Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | This urgent warning illuminates when a severe system fault or critical failure is detected on the PC400, such as catastrophic engine or hydraulic issues. | Shut down the excavator immediately and investigate the root cause before restarting. | |
| Master Caution | AMBER | The master caution light appears for significant, but not emergency, faults detected by the PC400’s monitoring systems. | Review instrument panel messages and schedule service as soon as possible. | |
| Check Engine (MIL) | AMBER | Indicates a detected engine system malfunction or sensor issue specific to the PC400’s diesel powerplant. | Check for diagnostic trouble codes and arrange for engine inspection. | |
| Engine Oil Pressure | RED | Signals dangerously low engine oil pressure, risking severe engine damage in the PC400. | Stop the engine immediately and check oil level and leaks. | |
| Battery / Charging | RED | Indicates the alternator is not charging the battery or there is a severe electrical fault. | Inspect the charging system and battery connections before continuing operation. | |
| Coolant Temperature | RED | Warns of engine coolant overheating, which can cause head gasket or engine block damage in the PC400. | Shut down and allow the engine to cool; check coolant level and radiator for blockages. | |
| Hydraulic System | AMBER | Alerts to abnormal hydraulic fluid temperature or pressure, which may impact arm or boom operation. | Monitor hydraulic performance and check fluid levels and filters promptly. | |
| Hydraulic Oil | AMBER | Signals low hydraulic oil level or excessive contamination detected in the PC400’s reservoir. | Top off hydraulic oil and inspect for leaks or contamination. | |
| Low Fuel | AMBER | Indicates the fuel tank is nearing empty, risking engine shutdown during operation. | Refuel the machine at the next safe opportunity. | |
| Fuel Filter / Water Separator | AMBER | Signals water accumulation or excessive restriction in the fuel filter assembly. | Drain water separator and replace the filter if necessary. | |
| Water in Fuel | AMBER | Detected water contamination in the diesel fuel, which can harm injectors and the PC400’s fuel system. | Drain water separator and inspect fuel quality. | |
| DPF / Regeneration | AMBER | Indicates the diesel particulate filter requires regeneration due to soot buildup. | Follow on-screen prompts to initiate or complete regeneration. | |
| DEF / AdBlue | AMBER | DEF level is low or there is an issue with the dosing system, affecting emissions compliance. | Refill DEF tank and check system for faults. | |
| Engine Oil Temperature | RED | Indicates engine oil temperature is too high, risking lubrication failure in the PC400. | Stop operation and allow cooling; check oil level and cooling system. | |
| Air Filter | AMBER | Signals excessive restriction or clogging in the engine air filter. | Clean or replace the air filter element promptly. | |
| Service / Hour Meter | AMBER | Displays when scheduled maintenance is due based on machine operating hours. | Perform the recommended service per Komatsu PC400 maintenance schedule. | |
| Work Lights | BLUE | Indicates the PC400’s exterior work lights are switched on for visibility during nighttime or low-light operation. | No action required unless lights are not functioning as intended. | |
| Beacon / Rotating Light | BLUE | Shows that the warning beacon is active, alerting nearby personnel to machine operation. | Ensure beacon is functioning during site operation. | |
| Swing / Slew Lock | AMBER | Indicates the swing lock is engaged, preventing the upper structure from rotating. | Disengage swing lock before attempting to rotate the cab. | |
| Overload / Capacity | RED | Warns that the PC400 is lifting beyond its rated capacity, risking structural damage. | Lower the load immediately and reassess lifting technique. | |
| Door Open | AMBER | Indicates that the cab or engine compartment door is open while the PC400 is running. | Secure all doors before continuing operation. |
21 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Engine Oil Pressure
Common causes
- Severe oil leak
- Faulty oil pump
- Critically low oil level
What to do
Stop the PC400 immediately, check for visible leaks, verify oil level, and do not restart until the cause is addressed and oil pressure is restored.
Coolant Temperature
Common causes
- Coolant leak
- Radiator blockage
- Failed water pump
What to do
Allow the engine to cool, inspect coolant level and radiator, and repair any leaks or replace faulty components before resuming work.
Hydraulic System
Common causes
- Hydraulic fluid low
- Clogged hydraulic filter
- Pump or hose failure
What to do
Check and top up hydraulic oil, replace the filter if necessary, and inspect for external leaks or damaged hoses specific to the PC400.
Overload / Capacity
Common causes
- Attempting to lift too heavy a load
- Incorrect lifting point
- Malfunctioning load sensor
What to do
Immediately lower the load, verify the weight and lifting configuration, and inspect the PC400’s load monitoring system for proper operation.
Battery / Charging
Common causes
- Alternator failure
- Loose or corroded battery terminals
- Broken drive belt
What to do
Inspect alternator output, check battery connections, and replace any damaged belts to restore charging on the PC400.
Frequently Asked Questions
What should I do if the hydraulic system warning appears while operating the PC400?
Safely stop operation, check hydraulic oil level and filter, and inspect for leaks or abnormal noises before resuming work.
How often should I service the PC400 based on the hour meter?
Follow the Komatsu PC400 maintenance schedule, typically performing minor service every 250 hours and major service at 2000 hours or as indicated.
What does it mean if the DPF/Regeneration light stays on?
This means the diesel particulate filter needs regeneration; follow the on-screen prompts to complete the process or consult the manual if it persists.
Is the PC400 safe to operate with the master caution light on?
While not immediately dangerous, you should investigate the cause as soon as possible to prevent escalation to a critical failure.
Why would the water in fuel light illuminate on the PC400?
This indicates water has been detected in the fuel system; drain the water separator promptly to avoid injector or pump damage.