What is Liebherr Fault Code E117?

Liebherr Fault Code E117 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects a voltage signal from the coolant temperature sensor that falls outside the expected operating range, or when the sensor readings are inconsistent with actual engine operating conditions.

The coolant temperature sensor is a critical component in Liebherr excavators, providing real-time data to the ECM about engine thermal status. This information directly influences fuel injection timing, idle speed control, and cooling fan activation. When E117 appears, the ECM may default to a predetermined temperature value, potentially causing suboptimal engine performance, increased fuel consumption, or activation of engine protection protocols that limit machine productivity.

Common Symptoms

When fault code E117 is active on a Liebherr excavator, operators typically experience:

• Engine warning light illuminated on the instrument cluster, often accompanied by a temperature-related alert symbol
• Hard starting conditions, particularly when the engine is cold, due to improper fuel delivery calculations
• Cooling fan running continuously at high speed, even when the engine is cold or at normal operating temperature
• Reduced engine power or derate mode activation as a protective measure against perceived overheating
• Rough idle or hunting RPM as the ECM struggles to maintain proper fuel maps without accurate temperature data

Potential Causes

The most common technical reasons for E117 appearing on used Liebherr excavators include:

• Coolant temperature sensor failure due to internal element degradation or contamination exposure
• Damaged wiring harness or connector corrosion at the sensor connection point, especially near the engine block where heat cycling and vibration are constant
• Broken or frayed wires along the sensor circuit, particularly at harness routing points near the engine mounts or frame rails where rubbing occurs over time
• Poor ground connection affecting sensor signal integrity
• Coolant contamination or low coolant level causing erratic sensor readings
• ECM internal fault (less common) affecting the temperature input circuit processing

How to Troubleshoot and Fix Code E117

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, pay special attention to connector seal integrity, as years of thermal cycling can degrade rubber seals. Check the wiring harness for visible damage, chafing, or oil contamination along its entire length from sensor to ECM.

Step 2: Electrical Testing Using a digital multimeter, disconnect the coolant temperature sensor and measure its resistance. At room temperature (approximately 20°C/68°F), resistance should typically read between 2,000-3,000 ohms (consult your specific Liebherr service manual for exact specifications). Test the sensor at different temperatures if possible—resistance should decrease smoothly as temperature increases. Next, check for supply voltage at the connector (usually 5 volts reference from the ECM) and verify ground continuity with less than 1 ohm resistance.

Step 3: Circuit and Component Verification If sensor resistance is out of specification, replace the coolant temperature sensor with a genuine Liebherr part or OEM-equivalent component. If electrical values are correct, inspect the wiring harness for intermittent faults by gently flexing wires while monitoring resistance. For used machines, remove any protective loom and examine for wire-to-wire shorts or harness rub-through at mounting brackets. Use Liebherr diagnostic software (Liebherr LiDat) to monitor live sensor data and verify the ECM is receiving proper signals after repairs.

Step 4: System Reset and Verification After addressing the root cause, clear the fault code using diagnostic software and operate the machine through a complete thermal cycle. Monitor for code recurrence and verify proper cooling fan operation and engine performance across all temperature ranges.

Disclaimer: This guide provides general troubleshooting information for Liebherr excavators. Always consult your machine's specific service manual and consider professional diagnostic assistance for complex electrical issues or if you're uncertain about any procedure. Improper repairs can lead to engine damage or safety hazards.