What is Liebherr General Fault Code E107?

Fault Code E107 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading detected by the ECM (Engine Control Module). This code triggers when the electronic control system receives voltage signals outside the expected range from the coolant temperature sensor, or when the reported temperature doesn't correlate with actual operating conditions.

In Liebherr excavators, the coolant temperature sensor plays a critical role in engine management. The ECM uses this data to adjust fuel injection timing, control engine warm-up cycles, activate cooling fan operation, and protect the engine from overheating damage. When E107 appears, the system may revert to default temperature values, potentially causing inefficient combustion, increased emissions, and inadequate engine protection. For used machines operating in demanding conditions, ignoring this code can lead to catastrophic engine failure or reduced component lifespan.

Common Symptoms

• Engine warning light illuminated on the instrument cluster, often accompanied by a temperature gauge malfunction
• Hard starting or rough idle, especially during cold starts when the ECM cannot properly enrich the fuel mixture
• Cooling fan running continuously at high speed, regardless of actual engine temperature
• Engine derate or power limitation engaged as a protective measure, reducing available hydraulic power
• Black smoke from the exhaust due to improper fuel-air mixture calculations based on faulty temperature data

Potential Causes

The most common technical reasons for E107 on used Liebherr excavators include:

• Coolant temperature sensor failure due to internal element degradation or contamination from coolant additives
• Wiring harness damage at known rub points near the engine block or cylinder head, particularly where harnesses contact sharp edges or moving components
• Corroded or loose connector pins at the sensor plug, especially on machines exposed to harsh environments or poor maintenance
• ECM internal fault or software corruption, though less common than sensor-circuit issues
• Incorrect sensor installation after previous repairs, including overtightened sensors causing internal damage or undertightened sensors allowing air infiltration
• Coolant system contamination causing sensor coating or electrical conductivity changes in the coolant itself

How to Troubleshoot and Fix Code E107

Step 1: Visual Inspection Begin by locating the coolant temperature sensor (typically mounted on the engine block or cylinder head). Inspect the wiring harness from sensor to ECM for obvious damage, chafing, or burns. On used excavators, pay particular attention to harness routing near heat sources and moving parts. Check the connector for corrosion, bent pins, moisture intrusion, or loose retention clips.

Step 2: Electrical Testing Disconnect the sensor and use a digital multimeter to measure resistance across the sensor terminals. Compare readings against Liebherr's specification chart (resistance should decrease as temperature increases—typically 2,000-3,000 ohms at 20°C). Test harness continuity from the sensor connector back to the ECM, checking for shorts to ground or open circuits. Measure supply voltage at the sensor connector (should be approximately 5 volts reference voltage from the ECM).

Step 3: Component Replacement and Verification If sensor resistance is out of specification or harness damage is found, replace the faulty component using genuine Liebherr parts to ensure proper calibration. Apply dielectric grease to connector pins before reassembly to prevent future corrosion—critical for used machines. After replacement, clear the fault code using Liebherr diagnostic software (LiDat) or a compatible scan tool, then monitor the system during a complete warm-up cycle to verify proper operation and ensure no code recurrence.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Liebherr service manual for your specific model and serial number. Complex electrical diagnostics should be performed by certified technicians with proper diagnostic equipment to avoid further damage to electronic systems.