Komatsu PC210-10 Fault Code E-6: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code E-6?

Fault Code E-6 on the Komatsu PC210-10 excavator indicates an Engine Controller (ECM) communication error or engine overheat condition. This code specifically relates to abnormal temperature sensor readings or a breakdown in communication between the engine control module (ECM) and the main monitor panel.

This fault is critical because the PC210-10's SAA6D107E-1 engine relies on precise thermal management to prevent catastrophic damage. When the ECM detects coolant temperatures exceeding safe operating parameters (typically above 105°C/221°F) or loses sensor input, it triggers E-6 to protect engine components from heat-related failure. In used excavators, this code often appears due to degraded sensors or wiring harness issues common in machines with 5,000+ operating hours.

Common Symptoms

• Engine warning light illuminated on the monitor panel with audible alarm
• Automatic engine power derate (reduced RPM and hydraulic response)
• Elevated coolant temperature gauge readings or erratic temperature display
• Engine auto-shutdown in severe cases to prevent thermal damage
• Intermittent code activation during high-load operations or hot ambient conditions

Potential Causes

The most common technical causes for E-6 on used PC210-10 excavators include:

• Coolant temperature sensor failure – The primary sensor located on the thermostat housing degrades over time, sending false high-temperature signals
• Damaged wiring harness – Known rub points near the engine mount and turbocharger often cause wire insulation breakdown
• ECM communication fault – Corrosion on the 38-pin ECM connector or loose ground connections (common on machines stored outdoors)
• Actual engine overheating – Clogged radiator cores, failed water pumps, or collapsed coolant hoses
• Faulty thermostat stuck closed, restricting coolant flow
• Low coolant levels due to external leaks or inadequate maintenance

How to Troubleshoot and Fix Code E-6

Step 1: Visual Inspection Check coolant level in the expansion tank with engine cold. Inspect all coolant hoses, radiator fins, and look for visible leaks. On used machines, examine the wiring harness routing from the temperature sensor to the ECM for chafing, especially where it crosses the engine block near the fuel injection pump.

Step 2: Test the Coolant Temperature Sensor Locate the sensor on the thermostat housing (upper front of engine). Disconnect the 2-pin connector and measure resistance using a digital multimeter. At 20°C (68°F), resistance should read approximately 2,400-2,600 ohms. Compare readings against Komatsu's temperature-resistance chart. Check connector pins for corrosion or moisture intrusion—extremely common in high-hour used excavators.

Step 3: Verify ECM Communication Using Komatsu KOMTRAX diagnostic software or a compatible scan tool, monitor live coolant temperature data. Compare the ECM reading to actual engine temperature (use an infrared thermometer on the thermostat housing). A variance greater than 10°C indicates sensor or wiring problems. Inspect the ECM ground cable (G101 location behind cab) for tightness and corrosion.

Step 4: Test Actual Cooling System Function If sensor readings are accurate, verify the cooling system operates correctly. Check radiator cap pressure rating (recommended: 88 kPa/13 PSI), test water pump operation, and confirm the thermostat opens at 82°C. Flush the cooling system if the machine has unknown maintenance history.

Step 5: Clear Code and Monitor After repairs, clear the fault code using diagnostic software. Run the machine under load for 30 minutes while monitoring coolant temperature. For used excavators, replace the coolant temperature sensor preemptively if the machine has over 8,000 hours—sensor failure is highly predictable at this interval.

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Disclaimer: This guide provides general troubleshooting information for Code E-6. Always consult the official Komatsu service manual for your specific machine serial number. If unfamiliar with electrical diagnostics or cooling system repair, contact a certified Komatsu technician to prevent further damage.