What is Doosan Excavator Fault Code E000106-03?

Fault Code E000106-03 indicates a malfunction in the engine coolant temperature sensor circuit, specifically a voltage signal that is reading abnormally high or out of the expected range. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects that the coolant temperature sensor is sending a signal above the manufacturer's specified threshold, typically suggesting an open circuit, damaged sensor, or wiring issue.

The engine coolant temperature (ECT) sensor plays a critical role in Doosan excavators by providing real-time temperature data to the ECM. This information directly influences fuel injection timing, idle speed control, and engine protection protocols. When E000106-03 activates, the ECM may default to a failsafe temperature value, potentially causing suboptimal engine performance, increased fuel consumption, or activation of engine protection modes that limit machine productivity.

Common Symptoms

When fault code E000106-03 is active, operators typically experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Hard starting or rough idle, especially during cold starts when accurate temperature readings are crucial
• Engine running rich (black exhaust smoke) due to ECM assuming cold engine conditions
• Reduced engine power or derate mode activation to prevent potential overheating damage
• Cooling fan running continuously at maximum speed regardless of actual engine temperature

Potential Causes

The most common technical causes for E000106-03 in used Doosan excavators include:

• Failed coolant temperature sensor due to internal element degradation or contamination from coolant additives
• Open circuit in the sensor wiring harness, particularly at flex points near the engine block where vibration causes wire fatigue
• Corroded or loose connector terminals at the ECT sensor plug, especially common in machines exposed to harsh environments
• Damaged sensor ground circuit or poor ground connection to the engine block
• ECM internal fault (rare) affecting the sensor input circuit
• Previous repair attempts using incorrect sensor specifications or aftermarket sensors with incompatible resistance curves

How to Troubleshoot and Fix Code E000106-03

Step 1: Visual Inspection Begin by locating the coolant temperature sensor (typically mounted on the engine block or thermostat housing). Inspect the sensor connector for corrosion, moisture intrusion, or damaged pins. On used excavators, check the wiring harness for signs of rubbing against engine components, heat damage, or previous repair splices that may have failed.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. Compare readings against Doosan's specifications (typically 2,000-3,000 ohms at 68°F/20°C). An infinite resistance reading confirms sensor failure. Check the harness-side connector for supply voltage (typically 5V reference) and verify ground continuity to the ECM with resistance below 5 ohms.

Step 3: Circuit Verification With the sensor disconnected, check for short circuits between the signal wire and battery voltage or ground. Inspect the harness routing for wear points where insulation may have abraded through. For used machines, pay special attention to areas where harnesses pass through bulkheads or near moving components.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Doosan or OEM-equivalent sensor matching the correct part number. Apply dielectric grease to connector terminals before reassembly. Clear the fault code using Doosan diagnostic software (DMS or G-SCAN) and perform a test cycle to verify repair.

Disclaimer: This guide provides general troubleshooting information. Always consult the manufacturer's service manual for your specific model and serial number. Complex electrical diagnostics should be performed by qualified technicians with appropriate training and equipment.