What is Liebherr Excavator Fault Code E108?

Liebherr Fault Code E108 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible temperature reading detected by the Electronic Control Module (ECM). This diagnostic trouble code (DTC) is triggered when the ECM receives voltage signals outside the expected range from the coolant temperature sensor, or when the sensor data doesn't correlate with actual operating conditions.

The coolant temperature sensor plays a critical role in Liebherr excavators by monitoring engine thermal conditions and relaying real-time data to the ECM. This information directly influences fuel injection timing, idle speed adjustments, engine warm-up protocols, and cooling fan activation. When E108 appears, the ECM may default to a predetermined temperature value, potentially causing inefficient combustion, increased fuel consumption, and premature engine wear. For used excavators, this code often signals age-related sensor degradation or wiring harness damage from years of vibration and heat exposure.

Common Symptoms

When Code E108 is active, operators typically experience:

• Check Engine Light or warning indicator illuminated on the instrument cluster
• Hard starting conditions, especially during cold weather, as the ECM cannot optimize fuel delivery
• Rough idle or irregular engine RPM during warm-up phases
• Cooling fan running continuously or not activating when needed
• Reduced engine power or derate mode engagement to prevent potential overheating damage

Potential Causes

The most common technical reasons for E108 on used Liebherr excavators include:

• Failed coolant temperature sensor due to internal resistance drift or element contamination
• Damaged wiring harness or connector corrosion at the sensor plug, particularly where harnesses route near hot exhaust components
• Shorted or open circuits in the sensor signal wire or ground return path
• Coolant contamination causing sensor element fouling or inaccurate readings
• ECM internal fault (rare, but possible in high-hour machines with moisture intrusion)
• Improper sensor installation or wrong replacement part specification after previous repairs

How to Troubleshoot and Fix Code E108

Step 1: Visual Inspection Begin by locating the coolant temperature sensor (typically mounted on the engine block or thermostat housing). Inspect the connector for corrosion, bent pins, moisture intrusion, or damaged seals. On used excavators, check the wiring harness along its entire route for abrasion points, especially where it contacts frame members or passes near the turbocharger.

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 circuit continuity from the ECM connector to the sensor plug, and check for shorts to ground using the ohm setting.

Step 3: Live Data Analysis Connect Liebherr diagnostic software (LiDat or equivalent) to monitor real-time coolant temperature readings. Compare the displayed temperature against an infrared thermometer measurement of the actual coolant. A variance greater than 10°C indicates sensor failure or ECM calibration issues.

Step 4: Component Replacement If testing confirms sensor failure, replace with OEM or equivalent-specification parts. Apply dielectric grease to connector terminals to prevent future corrosion. For used machines, consider replacing the entire sensor pigtail if wiring shows heat damage or brittleness.

Step 5: System Verification Clear the fault code, run the engine through multiple thermal cycles, and verify the code doesn't return. Monitor cooling system performance under load conditions.

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Disclaimer: This guide provides general troubleshooting information. Always consult Liebherr technical documentation and qualified diesel technicians for machine-specific procedures. Improper diagnostics may cause additional system damage or safety hazards.