What is Liebherr General Fault Code E106?

Fault Code E106 on Liebherr excavators indicates a malfunction in the engine cooling system, specifically related to coolant temperature sensor circuit issues or abnormal coolant temperature readings. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects voltage signals outside the expected range from the coolant temperature sensor or when actual coolant temperatures exceed safe operating thresholds.

This code is critical for Liebherr machines because the engine's performance, fuel injection timing, and protective shutdown systems all rely on accurate coolant temperature data. When E106 activates, the ECM may enter a derated power mode to prevent catastrophic engine damage from overheating, directly impacting productivity and potentially leading to expensive repairs if ignored.

Common Symptoms

When fault code E106 is active, operators typically experience:

• Engine warning light or coolant temperature warning illuminated on the instrument cluster
• Reduced engine power (derate mode) or limited hydraulic function to protect the engine
• Engine fan running continuously at high speed, even during light operation
• Difficulty starting or rough idle, particularly when the engine is cold
• Premature engine shutdown or failure to start if coolant temperature exceeds critical limits

Potential Causes

Several technical issues common in used Liebherr excavators can trigger E106:

• Faulty coolant temperature sensor due to internal sensor element degradation or contamination from old coolant
• Damaged or corroded wiring harness at the sensor connector, especially where the harness routes near hot engine components or moving parts
• Low coolant level or air pockets in the cooling system causing inaccurate temperature readings
• Thermostat failure preventing proper coolant circulation and causing genuine overheating conditions
• ECM calibration issues or software glitches, particularly in older machines with outdated firmware
• Corroded ground connections affecting sensor circuit integrity, common in high-hour machines

How to Troubleshoot and Fix Code E106

Step 1: Visual Inspection and Coolant Level Check Begin by inspecting the coolant level in the expansion tank and radiator. Check for visible leaks, damaged hoses, or signs of coolant contamination. On used excavators, examine the wiring harness routing from the coolant temperature sensor to the ECM, looking specifically for chafing, burns, or corrosion at connector pins.

Step 2: Test the Coolant Temperature Sensor Using a digital multimeter, disconnect the coolant temperature sensor connector and measure resistance across the sensor terminals. Compare readings against Liebherr's specification chart (typically 2,000-3,000 ohms at 20°C). Also check for proper voltage supply (usually 5V reference) from the ECM at the harness connector.

Step 3: Inspect Wiring and Ground Circuits Check continuity between the sensor connector and ECM pins using wiring diagrams. Test for shorts to ground or power. On used machines, pay special attention to connector corrosion—clean contacts with electrical cleaner and apply dielectric grease.

Step 4: Verify Cooling System Operation If sensor readings are normal, test the thermostat function and verify proper coolant flow. Use Liebherr diagnostic software to monitor live coolant temperature data while the engine warms up, confirming the thermostat opens at the correct temperature.

Step 5: Clear Code and Monitor After repairs, clear the fault code using diagnostic software and operate the machine through multiple temperature cycles to ensure the issue is resolved.

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Disclaimer: This guide provides general troubleshooting information. Always consult Liebherr service manuals and qualified diesel technicians for your specific machine model. Improper diagnostics can lead to further damage or safety hazards.