What is Liebherr General Fault Code E445?

Fault Code E445 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading detected by the Engine Control Module (ECM). This diagnostic trouble code typically triggers when the ECM receives voltage signals outside the expected range from the coolant temperature sensor (CTS), or when the sensor reading doesn't correlate with actual operating conditions.

In Liebherr excavators, the coolant temperature sensor plays a critical role in engine management, directly influencing fuel injection timing, idle speed control, and engine protection protocols. The ECM relies on accurate temperature data to optimize combustion efficiency and prevent overheating damage. When E445 activates, the system may default to a predetermined temperature value, potentially affecting machine performance and increasing wear on engine components.

Common Symptoms

• Check Engine light or malfunction indicator illuminated on the instrument panel
• Engine running in derate mode with reduced power output to protect internal components
• Hard starting conditions, especially during cold weather operation, due to incorrect fuel delivery calculations
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Abnormal idle characteristics including hunting or unstable RPM fluctuations

Potential Causes

The most common technical reasons for E445 on used Liebherr excavators include:

• Coolant temperature sensor failure due to internal resistance drift or element degradation (common in machines with 5,000+ operating hours)
• Wiring harness damage at known rub points near the engine block or cylinder head where vibration causes insulation wear
• Corroded or loose electrical connectors at the sensor or ECM interface, particularly on machines stored outdoors or operated in wet environments
• ECM internal fault affecting the temperature monitoring circuit (less common but possible in older units)
• Coolant contamination causing sensor fouling or coating that affects reading accuracy
• Open or short circuits in the sensor signal or ground wires

How to Troubleshoot and Fix Code E445

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 visible damage, abrasion points, or evidence of previous repairs. Check connector terminals for corrosion, bent pins, or moisture intrusion—critical on used excavators with extended service history.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance at ambient temperature (typically 2,000-3,000 ohms at 20°C, but consult Liebherr specifications). Compare readings against the manufacturer's temperature-resistance chart. Test circuit continuity from the sensor connector to the ECM, checking for open circuits or shorts to ground.

Step 3: Live Data Analysis Connect Liebherr diagnostic software (LiDat or equivalent) to monitor real-time coolant temperature values. Compare displayed temperatures with actual engine conditions using an infrared thermometer. A significant discrepancy confirms sensor or circuit failure.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Liebherr sensor to ensure proper calibration. Before installation on used equipment, apply dielectric grease to connector terminals and verify coolant system integrity. Clear codes and perform a cold-start test cycle to verify repair.

Disclaimer: This guide provides general troubleshooting information. Complex electrical diagnostics should be performed by qualified technicians with proper equipment. Always consult official Liebherr service documentation and safety procedures before performing repairs.