You may encounter this situation: when you are operating your Komatsu equipment, but find its dashboard flashing with a piercing alarm. What’s going wrong? Can I keep working? What does this symbol even mean? This guide will have you covered. We’ll break down the essential Komatsu warning light symbols using a simple “traffic light” rule, explain what specific Komatsu fault codes mean, and walk through real-life examples to show you how to troubleshoot these issues like a pro.
Knowing the Core Komatsu Warning Light Symbols: The Three-Color Rule
The fastest way to assess any warning is by its color. This simple system tells you the urgency at a glance.
RED WARNING LIGHTS: STOP IMMEDIATELY!
Meaning: A red light signifies a critical failure. Continuing to operate risks immediate, severe damage to the machine or a serious safety incident.
Your Action: Stop all work instantly. Move the machine to a safe, level surface and shut down the engine as soon as it is safe to do so. Do not restart until the problem is resolved.
1. Engine Oil Pressure Warning
- Icon: An oil can with a drip.
- What It Means: The engine’s internal components are not receiving enough lubrication. This is the mechanical equivalent of a heart attack.
- Why It’s Critical: Without oil pressure, metal grinds against metal, causing catastrophic engine failure within minutes.
- Immediate Action: Shut the engine off immediately. Check the oil level on the dipstick.
2. Radiator Coolant Level Warning
- Icon: A symbol of a radiator with wavy lines and a downward arrow.
- What It Means: The coolant level in the plastic overflow tank (reservoir) is below the minimum safe level.
- Real-World Scenario: The Non-Stop Beeping PC200-8. Recently, on a popular heavy equipment forum, an operator with a Komatsu PC200-8 posted about a red light and a non-stop “beep beep beep” alarm. The culprit? This exact warning light. It’s one of the most common red-light alarm operators encountered.
- The Standard Fix: The first and most obvious step is to let the engine cool down, then check the coolant level in the overflow tank and top it up to the “Full” line.
What If Topping Up Doesn’t Work?
This is a frequent problem. Another operator on the forum faced the same alarm on his PC200LC-7, but his tank was already full. If you find yourself in this situation, here’s how to troubleshoot:
- Check the Sensor Connection
- Inspect the Float: If the float is stuck in the “low” position, it will trigger the alarm even when the tank is full.
- Test the Sensor Circuit: Use a small piece of wire (a paperclip can work) to create a “jumper” that connects the two pins inside the electrical connector. If the alarm and red light turn off, you have confirmed the problem is the sensor/float assembly in the tank.
- The Solution: In the forum user’s case, the fix was simple and affordable. He ordered a brand new overflow tank, which came with a new float and sensor already installed. Replacing the tank completely solved the problem.
3. Engine Coolant Temperature Warning
- Icon: A thermometer submerged in liquid.
- What It Means: This is different from the coolant level warning. This light means the engine itself is actually overheating. A common cause is a faulty component, and it’s wise to know how to tell if your water pump or thermostat is failing.
- Why It’s Critical: Extreme heat can warp the cylinder head, blow a head gasket, and seize the engine, leading to a complete rebuild.
- Immediate Action: Stop work, but you may let the engine idle for a minute to circulate coolant and cool down. Never open the radiator cap while the engine is hot.
4. Hydraulic Oil Temperature Warning
- Icon: A gear or wavy lines inside a thermometer.
- What It Means: The hydraulic fluid is too hot, losing its ability to lubricate and protect expensive pumps and valves. This can be a sign of impending hydraulic pump failure.
- Immediate Action: Lower all attachments to the ground and let the engine idle to help the system cool. If the temperature doesn’t drop, shut down.
YELLOW/AMBER CAUTION LIGHTS: INVESTIGATE SOON
Meaning: A yellow light is a pre-warning. The machine can continue to operate, but the system requires attention. Do not ignore these warnings.
- Fuel Level Warning: (Icon: A fuel pump) Time to refuel. Running a diesel engine dry can require bleeding the fuel system.
- Air Filter Clogging: (Icon: A filter with dots) The engine is being “suffocated.” This leads to low power and black smoke. Clean or replace the filter.
- Hydraulic/Transmission Filter Clogging: (Icon: A filter symbol with a gear or bypass arrow) Contaminants are building up. Ignoring this can cause dirty oil to circulate, accelerating wear. Schedule a filter change.
- DPF / SCR System Warning: (Icon: An exhaust pipe with dots or “DEF”) Relates to the Komatsu SCR system or Diesel Particulate Filter. The machine needs to perform a “regeneration” to burn off soot. Follow the on-screen instructions and do not shut down the engine during this process.
GREEN/BLUE INDICATOR LIGHTS: SYSTEM IS ACTIVE
These are purely informational. No action is needed.
- Pre-heat Indicator (Icon: A spiral coil): Glow plugs are warming the engine. Wait for it to turn off before starting.
- Work Mode (Icon: “P”, “E”, etc.): Shows your selected power or economy mode.
What Do Komatsu Fault Codes Mean?
While the colors give you the urgency, the complete system of Komatsu Warning Light symbols also includes alphanumeric codes for more specific diagnostics. Sometimes, a warning light is accompanied by this code. It gives a more specific diagnosis than the light alone, similar to the system of Kubota error codes we’ve covered previously.
This is not a complete Komatsu fault codes list, but here are common examples:
- L01 Komatsu Code / Komatsu Error Code L01: A general, low-priority system abnormality.
- L03 Komatsu Code / Komatsu Error Code L03: Often points to an electrical fault in the swing brake or travel alarm circuit.
- L04 Komatsu Code / LO4 Code Komatsu: A more specific fault within the travel alarm system.
- E03 Komatsu Code: Indicates a fault in the parking brake or swing brake system.
- E15 Komatsu Code: Signals a serious error with the engine controller. The engine may have reduced power or fail to start.
- CA428 Komatsu Code: A critical warning for water detected in the fuel. Stop and drain the water separator immediately to prevent damage to your fuel injectors.
- “Adjuster Overload” Message: A text warning, not a code. You are lifting a load that exceeds the machine’s safe limits. Reduce the load to clear the message.
Frequently Asked Questions
Where can I find a complete list of Komatsu Warning Light symbols and fault codes?
The only 100% accurate source is the official Operation & Maintenance or Service Manual for your specific machine model. Komatsu codes can vary between models.
How to clear codes on a Komatsu excavator?
Minor codes may clear themselves after the issue is fixed. However, critical fault codes (especially “E” codes) must be diagnosed and repaired by a qualified technician who can then clear the code from the controller.
What’s the most important takeaway for a new operator?
Respect the lights. Red means stop, yellow means check. As we saw in the real-world example, even a simple problem can have a tricky cause. Systematic troubleshooting is key. And always keep your operator’s manual in the cab—it is the ultimate guide to your specific machine.
What You Need to Do After Diagnosis
Knowing the problem is half the battle; getting the right part is the other. Whether your dashboard shows a CA428 code demanding a new sensor, a persistent filter warning, or a critical E15 error pointing to the controller, finding the solution is simple.
At FridayParts, we get you back to work faster with fast, global shipping on all our OEM-quality parts. Order with complete confidence thanks to our industry-leading 1-year warranty and easy returns. Don’t let a warning light stop your project. Find your solution at FridayParts and keep your Komatsu running strong.
