What is Komatsu PC100-6 Fault Code E316?

Fault Code E316 on the Komatsu PC100-6 indicates a malfunction in the engine overheat protection system, specifically related to the coolant temperature sensor circuit or excessively high coolant temperature readings. This code triggers when the Engine Control Module (ECM) detects that coolant temperature has exceeded safe operating limits (typically above 105-110°C) or when there's an electrical fault in the temperature sensing circuit.

This code is critical for the PC100-6 because prolonged operation under overheat conditions can cause severe engine damage, including warped cylinder heads, blown head gaskets, or cracked engine blocks. The ECM may initiate engine derate or automatic shutdown to prevent catastrophic failure, making immediate diagnosis essential for protecting your investment in used machinery.

Common Symptoms

• Coolant temperature warning light illuminated on the instrument panel, often accompanied by an audible alarm
• Engine power derate or automatic reduction in engine RPM to protect components from thermal damage
• Abnormal engine temperature gauge readings showing extremely high or erratic fluctuations
• Steam or coolant vapor visible from the radiator or overflow tank during operation
• Loss of hydraulic performance due to reduced engine power output when protection mode activates

Potential Causes

The E316 code on used PC100-6 excavators typically stems from several age-related issues. Coolant temperature sensor failure is common after years of heat cycling, causing inaccurate readings or open circuits. Wiring harness deterioration near the engine block—where vibration and heat cause insulation breakdown—creates intermittent electrical faults.

Actual overheating conditions caused by clogged radiator cores, failed water pumps, or stuck thermostats are frequent in older machines with deferred maintenance. Corroded sensor connectors from coolant leaks or environmental exposure create high resistance in the circuit. Low coolant levels due to degraded hoses or leaking gaskets trigger genuine overheat conditions that activate E316.

How to Troubleshoot and Fix Code E316

Step 1: Visual Inspection and Coolant Level Check Begin by inspecting coolant level in the radiator and overflow tank when the engine is cool. Check for visible leaks around hoses, water pump seals, and radiator connections. On used excavators, inspect the wiring harness running to the coolant temperature sensor for chafing, burns, or cracked insulation common at engine mounting points.

Step 2: Electrical Circuit Testing Using a digital multimeter, measure the coolant temperature sensor resistance. The sensor (typically located on the thermostat housing) should read approximately 2,000-3,000 ohms at 20°C. Check for voltage supply at the sensor connector (usually 5V reference from the ECM). Inspect connector pins for corrosion or bent terminals—a prevalent issue in older machines.

Step 3: Cooling System Functional Test If electrical checks pass, test actual cooling system operation. Verify the thermostat opens properly (typically at 82°C), inspect the radiator for internal blockage, and confirm water pump operation. Use Komatsu diagnostic software or a compatible scan tool to monitor real-time coolant temperature versus sensor readings to identify discrepancies.

For used excavators, always check for previous repair attempts, aftermarket sensor installations, or harness modifications that may cause compatibility issues before replacing the ECM.

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Disclaimer: This guide provides general troubleshooting information. Always consult qualified diesel mechanics or authorized Komatsu service centers for complex diagnostics and repairs involving engine control systems.