Komatsu SK820-5 Warning Lights and Symbols (Meaning and Fixes)

The Komatsu SK820-5 instrument cluster provides critical machine status through a combination of analog gauges and multi-function LCD. Designed for loader and backhoe operations, it monitors engine, hydraulic, and electrical systems to ensure maximum uptime.

How to read the colors: Red indicates stop and immediate action required; amber signals caution or service needed; green/blue confirms active functions or normal operation.

Komatsu SK820-5 Warning Light Symbols

SymbolNameColorWhat it meansWhat to do
Master Warning (Stop)REDA critical system fault detected on the SK820-5 that requires immediate engine shutdown to prevent damage.Stop the engine and contact Komatsu dealer support.
Master CautionAMBERA non-critical warning light on the SK820-5, indicating that one or more systems need attention soon.Check the LCD display for fault codes and schedule service if persistent.
Check Engine (MIL)AMBEREngine electronic control system has logged a fault code on the SK820-5, which may affect performance or emissions.Read engine fault codes using the diagnostic mode; contact your dealer if the light stays on.
Engine Oil PressureREDEngine oil pressure is below safe minimum on the SK820-5, risking serious engine damage.Stop the engine immediately and check oil level; if okay, do not restart – call for service.
Battery / ChargingREDAlternator not charging properly or battery voltage is low on the SK820-5 electrical system.Check battery connections and alternator belt; if light remains, have electrical system tested.
Coolant TemperatureREDEngine coolant exceeds normal operating range on the SK820-5, risk of overheating.Stop the engine, let it cool, check coolant level and radiator for blockages.
ATTransmission TempAMBERTransmission/hydraulic fluid temperature is high on the SK820-5; reduce load until light goes out.Shift to low range or park and idle to cool down; if persistent, check fluid levels.
PParking BrakeREDParking brake is engaged on the SK820-5; machine will not move until released.Release parking brake before operating; if light stays off, brake switch may need adjustment.
Glow Plug / PreheatAMBERGlow plugs are heating on the SK820-5 diesel engine; wait for light to go out before starting.Turn key to preheat position and wait; if light fails, check glow plug relay.
Water in FuelAMBERWater has accumulated in the fuel filter/water separator of the SK820-5; drain promptly.Drain water from the fuel separator bowl; if light persists, replace filter and prime system.
Low FuelAMBERFuel level is low on the SK820-5; refill soon to avoid air in system.Add diesel fuel; do not run tank dry to prevent priming issues.
Hydraulic SystemAMBERHydraulic system issue detected on the SK820-5, such as low fluid or high temperature.Check hydraulic oil level and temperature; if lamp stays on, inspect for leaks.
Fasten Seat BeltREDOperator seat belt not fastened on the SK820-5; machine functions may be limited.Fasten your seat belt; if light remains, check seat belt switch.
Air FilterAMBEREngine air filter is clogged on the SK820-5, reducing air flow and power.Clean or replace engine air filter element as soon as possible.
Service / Hour MeterGREENScheduled service interval reminder on the SK820-5; appears at preset hours.Perform required maintenance per operator's manual; reset after service.
Work LightsBLUEWork lights are switched on for the SK820-5, improving visibility in low-light conditions.None – indicates normal operation; turn off when not needed to save battery.
Beacon / Rotating LightGREENRotating beacon is active on the SK820-5, signaling machine is in operation.None – keep beacon on when machine is moving; turn off if stationary for long periods.
Swing / Slew LockAMBERSwing lock pin is engaged on the SK820-5 backhoe attachment; upper structure cannot rotate.Release swing lock before operating backhoe swing function.
Differential LockGREENDifferential lock is engaged on the SK820-5 for maximum traction in soft ground.Disengage differential lock when on hard surfaces to avoid drive line damage.

19 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.

Most Important Warning Lights

Engine Overheating

Common causes

  • Low coolant level
  • Radiator blockage
  • Failed thermostat

What to do

Stop the SK820-5 immediately. Check coolant level when cool, clean radiator fins of debris. If persistent, inspect thermostat and water pump – contact Komatsu dealer.

Hydraulic System Failure

Common causes

  • Low hydraulic oil
  • Contaminated fluid
  • Failed pump

What to do

Check hydraulic oil level and condition on the SK820-5; prime system if necessary. If light stays on, do not operate – have dealer test pump pressure.

Fuel System Water Contamination

Common causes

  • Water in fuel tank
  • Dirty fuel
  • Faulty water separator

What to do

Drain water from the fuel filter bowl on the SK820-5. Replace fuel filter and fill with clean diesel; if light repeats, inspect fuel tank for water ingress.

Engine Oil Pressure Loss

Common causes

  • Low oil level
  • Oil pump failure
  • Worn bearings

What to do

Shut off the SK820-5 engine. Verify oil level and condition; if adequate, do not restart – internal damage likely, contact dealer for diagnosis.

Frequently Asked Questions

Why does my SK820-5 show a master caution and a hydraulic system light together?

The SK820-5 master caution accompanies any secondary warning. The hydraulic light suggests low fluid or temperature; check hydraulic oil level and look for leaks. If both persist, a sensor may need replacement.

How do I reset the service hour meter light on the SK820-5?

After performing the required maintenance, turn the key to ON, then press and hold the mode/reset button on the instrument cluster for 5 seconds until the light turns off.

The glow plug light stays on after starting the SK820-5 – what should I do?

If the glow plug light remains on with engine running, it indicates a preheat system fault. Check glow plug relay and wiring; replace any failed glow plugs. Avoid prolonged cranking.

What does the amber transmission temperature light mean on the SK820-5?

It warns that transmission or hydraulic fluid is too hot. Reduce load immediately – shift to low range or park and idle. If light persists, check fluid level and cooler for blockage.

How can I check fault codes on the SK820-5 LCD display?

Turn key to ON and the LCD will show active warnings. For stored codes, press and hold the 'menu' and 'set' buttons simultaneously for 3 seconds; the display will cycle through fault codes.