What is Yanmar DX75-9C Fault Code E000110-02?

Fault Code E000110-02 on the Yanmar DX75-9C excavator indicates a malfunction in the engine coolant temperature sensor circuit, specifically a low voltage condition or open circuit detected by the Engine Control Module (ECM). This code signals that the ECM is receiving an abnormally low signal from the coolant temperature sensor, which monitors engine thermal conditions to optimize fuel injection, timing, and protect against overheating.

This fault is critical for the DX75-9C because the Yanmar engine relies heavily on accurate coolant temperature data to regulate performance. Without proper temperature readings, the ECM may default to safe mode, limiting engine power and hydraulic response. For used excavators, this code often appears due to age-related wiring deterioration or sensor degradation from thermal cycling over thousands of operating hours.

Common Symptoms

When E000110-02 is active on your Yanmar DX75-9C, operators typically experience:

• Check engine warning light illuminated on the instrument panel
• Engine derate mode with noticeably reduced power output and slower hydraulic functions
• Hard starting or extended cranking, especially in cold conditions
• Rough idle or irregular engine performance during warm-up
• Cooling fan running continuously at high speed, regardless of actual engine temperature

Potential Causes

The most common technical reasons for this fault code on used DX75-9C excavators include:

• Faulty coolant temperature sensor with internal resistance breakdown (common after 5,000+ hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at connection points near the engine block where vibration causes wear
• Loose or corroded electrical connectors at the sensor or ECM terminals
• Open circuit in the signal wire due to harness chafing against frame components (known issue near the fuel filter mounting area)
• ECM internal fault (rare, but possible in high-hour machines)
• Low coolant level causing sensor exposure and intermittent readings

How to Troubleshoot and Fix Code E000110-02

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check coolant level first—low coolant can expose the sensor. Examine the wiring harness from sensor to ECM for visible damage, abraded insulation, or corrosion. On used excavators, pay special attention to harness routing where it contacts metal edges or passes near hot exhaust components.

Step 2: Electrical Testing Disconnect the coolant temperature sensor connector and use a digital multimeter to measure sensor resistance. A functional sensor typically reads 2,000-3,000 ohms at room temperature (refer to Yanmar specifications). Next, check for continuity in the signal wire from sensor connector to ECM pin (consult wiring diagram). Measure voltage supply at the sensor connector with ignition on—should read approximately 5 volts reference voltage from the ECM.

Step 3: Component Replacement and Verification If resistance is out of specification or wiring shows open circuit, replace the defective component. For used machines, always clean connector terminals with electrical contact cleaner and apply dielectric grease before reconnection. After repairs, clear the fault code using Yanmar diagnostic software or a compatible scan tool, then run the engine through temperature cycles to verify the fix.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Yanmar service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues.