What is Liebherr Excavator Fault Code E023?

Liebherr Fault Code E023 indicates a malfunction in the engine coolant temperature sensor circuit or an out-of-range coolant temperature reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an implausible signal from the coolant temperature sensor (CTS), typically due to an open circuit, short circuit, or sensor degradation.

The coolant temperature sensor is critical for Liebherr excavators because it directly influences fuel injection timing, engine warm-up protocols, and hydraulic oil temperature management. When E023 activates, the ECM may default to a pre-programmed temperature value, which can lead to inefficient combustion, increased emissions, and reduced hydraulic performance. For used excavators, this code often surfaces due to age-related sensor wear or harness deterioration from engine bay heat cycling.

Common Symptoms

When Code E023 is active, operators typically experience:

• Check Engine Light (CEL) or malfunction indicator lamp illuminated on the instrument cluster
• Engine derate mode or reduced power output, especially during cold starts
• Difficulty starting in cold weather conditions due to improper fuel enrichment
• Erratic temperature gauge readings or gauge stuck at cold/hot positions
• Increased fuel consumption and rough idling as the ECM compensates for missing data

Potential Causes

The most common technical causes for Code E023 on used Liebherr excavators include:

• Failed coolant temperature sensor due to internal resistance drift or element failure (common after 5,000+ operating hours)
• Corroded or loose connector pins at the CTS harness connection point near the thermostat housing
• Damaged wiring harness from rubbing against engine components, particularly where the harness routes near the cylinder head or exhaust manifold
• ECM internal fault or corrupted calibration data (rare but possible in older machines)
• Coolant contamination causing sensor element coating or degradation
• Voltage supply issues from the ECM 5-volt reference circuit

How to Troubleshoot and Fix Code E023

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor and its wiring harness for obvious damage. Check the connector at the sensor for corrosion, bent pins, or moisture intrusion—common issues in used excavators. Examine the harness routing for wear points where insulation may have rubbed through against metal edges or hot engine surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance at various temperatures. A typical Liebherr CTS shows approximately 2,500-3,000 ohms at 20°C (68°F) and decreases to 200-300 ohms at 80°C (176°F). Compare your readings to Liebherr specifications. Next, check the ECM reference voltage at the harness connector—it should read approximately 5 volts DC with the ignition on and sensor disconnected.

Step 3: Signal Testing with Diagnostic Software Connect Liebherr-approved diagnostic software (such as LiDat or compatible tools) to monitor live coolant temperature data. Compare the sensor reading to actual engine temperature using an infrared thermometer on the thermostat housing. A deviation greater than 10°C (18°F) indicates sensor failure.

Step 4: Component Replacement and Verification If testing confirms sensor failure, replace the coolant temperature sensor using genuine Liebherr parts to ensure proper resistance curves. For used excavators, always apply dielectric grease to connector pins to prevent future corrosion. After replacement, clear the fault code and perform a cold-start test cycle to verify proper ECM response. Inspect adjacent harnesses for damage that may cause recurring issues.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Liebherr service manual for your specific excavator model and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.