What is Doosan Excavator Fault Code E000108-02?

Fault Code E000108-02 indicates a low voltage condition detected in the Engine Coolant Temperature (ECT) sensor circuit on Doosan excavators. This diagnostic trouble code (DTC) specifically signals that the Engine Control Module (ECM) has measured a voltage reading below the expected threshold from the coolant temperature sensor, typically indicating an open circuit, sensor failure, or wiring issue.

The ECT sensor plays a critical role in engine management by providing real-time coolant temperature data to the ECM. This information directly influences fuel injection timing, idle speed control, and engine protection protocols. In Doosan excavators, accurate coolant temperature readings are essential for maintaining optimal engine performance, preventing overheating, and ensuring proper hydraulic system operation under varying load conditions.

Common Symptoms

When fault code E000108-02 is active, operators may experience:

• Check Engine Light or Engine Warning Indicator illuminated on the instrument cluster
• Hard starting or rough idle, especially during cold starts when the ECM defaults to predetermined values
• Poor fuel economy due to incorrect fuel mapping based on faulty temperature data
• Engine may enter derate mode or limp mode, limiting power output and hydraulic performance
• Cooling fan running continuously at high speed, regardless of actual engine temperature

Potential Causes

The most common technical reasons for E000108-02 in used Doosan excavators include:

• ECT sensor internal failure – sensor element degradation common in machines with 5,000+ operating hours
• Damaged or corroded wiring harness – particularly at known rub points near the engine block where harnesses contact metal surfaces
• Connector corrosion or moisture intrusion – especially in the sensor connector located near the thermostat housing
• Open circuit in sensor ground wire – ground wire breakage or poor ground connection at ECM
• ECM internal fault (rare) – damaged input circuit within the Engine Control Module itself
• Previous repair attempts causing intermittent connections or incorrect sensor installation

How to Troubleshoot and Fix Code E000108-02

Step 1: Visual Inspection Begin with a thorough physical inspection of the ECT sensor and its wiring harness. The sensor is typically located on the engine block near the thermostat housing. Check for obvious damage, coolant leaks around the sensor base, corroded connectors, or chafed wires. On used excavators, pay special attention to harness routing where cables may have rubbed against engine components over thousands of operating hours.

Step 2: Electrical Testing Disconnect the ECT sensor connector and use a digital multimeter to measure sensor resistance. At room temperature (68°F/20°C), resistance should typically read between 2,000-3,000 ohms (consult Doosan specifications for your exact model). Check for open circuit (infinite resistance) which confirms sensor failure. Next, inspect the wiring harness by measuring continuity from the sensor connector pins back to the ECM connector – you should see less than 5 ohms resistance on signal and ground wires.

Step 3: Voltage and Ground Verification With the ignition ON and sensor disconnected, measure voltage at the harness connector. You should see approximately 5 volts reference voltage from the ECM on the signal wire. If voltage is absent or incorrect, trace the harness for breaks or shorts. Verify the ground circuit has proper continuity to chassis ground. Corrosion on ground terminals is extremely common in used machines and often overlooked.

Step 4: Component Replacement and Verification If testing confirms sensor failure, replace the ECT sensor using a genuine Doosan or OEM-equivalent part. Apply appropriate thread sealant rated for coolant contact. After installation, clear the fault code using Doosan diagnostic software (DX-Connect or equivalent scan tool) and perform a test cycle. Monitor live data to confirm the ECM now receives proper temperature readings that correlate with actual engine temperature.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Doosan service manual for your specific excavator model. If you're unfamiliar with electrical diagnostics or lack proper tools, consult a certified heavy equipment technician to prevent further damage or safety hazards.