What is Liebherr General Fault Code E517?

Fault Code E517 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading detected by the Electronic Control Module (ECM). This diagnostic trouble code specifically relates to the engine's thermal management system, where the ECM receives incorrect, intermittent, or out-of-range signals from the coolant temperature sensor (CTS).

In Liebherr excavators, accurate coolant temperature monitoring is critical for proper fuel injection timing, engine protection protocols, and hydraulic oil temperature management. When the ECM cannot reliably determine engine temperature, it may initiate protective measures that significantly impact machine performance. This code is particularly common in used excavators where sensor degradation, wiring corrosion, or coolant contamination has occurred over thousands of operating hours.

Common Symptoms

• Amber engine warning light illuminated on the instrument cluster with possible audible alarm
• Engine operating in derate mode or limp mode, limiting RPM to approximately 1,500-1,800 to prevent potential overheating damage
• Erratic temperature gauge readings that fluctuate abnormally or display implausible values (extremely high or low)
• Hard starting conditions, especially in cold weather, due to improper fuel enrichment calculations
• Cooling fans running continuously at maximum speed regardless of actual engine temperature

Potential Causes

• Coolant temperature sensor failure due to internal resistance drift or element deterioration (common after 5,000+ operating hours)
• Damaged or corroded wiring harness between the CTS and ECM, particularly at connection points near the engine block where vibration and heat cycles cause wear
• Corroded or loose electrical connectors at the sensor or ECM, allowing moisture intrusion
• ECM internal fault affecting the temperature monitoring circuit (less common but possible in high-hour machines)
• Low coolant level or air pockets in the cooling system causing localized sensor exposure and false readings
• Contaminated coolant affecting sensor accuracy or causing sensor tip buildup

How to Troubleshoot and Fix Code E517

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor location (typically on the engine block or thermostat housing). Check the wiring harness for obvious damage, chafing against engine components, or heat damage. On used excavators, pay special attention to connector corrosion—disconnect and inspect both the sensor connector and ECM connections for green corrosion or bent pins.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the resistance across the CTS terminals with the sensor disconnected. Compare readings against Liebherr specifications (typically 2,000-3,000 ohms at 20°C, decreasing to 200-300 ohms at 80°C). If resistance is out of specification or reads open/short circuit, replace the sensor.

Step 3: Circuit Voltage and Continuity Check With the sensor disconnected and ignition on, measure reference voltage at the harness connector (should be approximately 5 volts). Check continuity between the sensor connector and ECM pins using wiring diagrams. Resistance should be less than 5 ohms; higher readings indicate wiring issues.

Step 4: Verify Coolant System Integrity Ensure proper coolant level and system pressure. Bleed air from the cooling system following Liebherr procedures. Contaminated or degraded coolant can coat the sensor tip, causing inaccurate readings.

Step 5: Clear Code and Monitor After repairs, clear the fault code using Liebherr diagnostic software (LiDat) and operate the machine through a complete heat cycle. Monitor for code recurrence, which may indicate ECM issues requiring dealer-level diagnostics.

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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 qualified technicians with proper diagnostic equipment.