What is Liebherr General Fault Code E118?

Fault Code E118 on Liebherr excavators indicates an Engine Coolant Temperature (ECT) Sensor Circuit Malfunction or an implausible signal from the coolant temperature monitoring system. This diagnostic trouble code is triggered when the Electronic Control Module (ECM) detects voltage readings outside the expected range or an intermittent signal from the coolant temperature sensor circuit.

This fault is critical because the ECT sensor provides essential data for fuel injection timing, engine warm-up cycles, and overall thermal management. When the ECM cannot accurately monitor coolant temperature, it may default to conservative operating parameters, reducing performance and potentially causing unnecessary component wear on used excavators with accumulated operating hours.

Common Symptoms

When Code E118 is active, operators typically experience:

• Check Engine light or malfunction indicator illuminated on the dashboard display
• Engine derate mode or reduced power output as the ECM enters fail-safe protection
• Difficult cold starts or extended cranking times, especially in cooler temperatures
• Erratic cooling fan operation, with fans running continuously regardless of actual engine temperature
• Black smoke from exhaust due to improper fuel mixture calculations based on faulty temperature readings

Potential Causes

The most common technical reasons for E118 on Liebherr equipment include:

• Failed ECT sensor due to internal element degradation (common on machines with 5,000+ operating hours)
• Corroded or loose connector pins at the sensor harness connection point
• Damaged wiring harness from rubbing against engine components or heat exposure near the exhaust manifold
• Contaminated coolant causing sensor element fouling or incorrect readings
• ECM calibration issues or software glitches (less common but documented on older control modules)
• Poor ground connections in the sensor circuit creating voltage inconsistencies

How to Troubleshoot and Fix Code E118

Step 1: Visual Inspection Begin by inspecting the ECT sensor connector located on the engine block (typically near the thermostat housing). Check for corrosion, coolant contamination, or damaged pins. On used excavators, examine the entire wiring harness for chafing, particularly where it routes near moving components or hot surfaces.

Step 2: Electrical Testing Using a digital multimeter, measure sensor resistance with the engine cold. Liebherr ECT sensors typically read 2,000-3,000 ohms at 20°C (check your specific model's service manual). Test circuit voltage at the ECM connector—you should see approximately 5 volts reference voltage from the control module.

Step 3: Component Replacement and Verification If resistance values are out of specification or the connector shows significant corrosion, replace the ECT sensor using OEM or quality aftermarket parts. Clear the fault code using Liebherr diagnostic software (LiDat or compatible interface) and perform a test cycle. For persistent codes, inspect ECM grounds and consider harness replacement if multiple rub-through points exist.

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