What is Liebherr General Fault Code E45?

Fault Code E45 on Liebherr excavators indicates a malfunction in the engine coolant temperature sensor circuit or an out-of-range temperature reading. This code is triggered when the Electronic Control Module (ECM) detects either an implausible voltage signal from the coolant temperature sensor, a complete circuit failure, or coolant temperatures exceeding safe operational parameters.

The coolant temperature sensor is critical for Liebherr's engine management system, as it directly influences fuel injection timing, engine protection protocols, and hydraulic oil temperature regulation. When E45 appears, the ECM may default to a predetermined temperature value, potentially causing suboptimal engine performance, increased fuel consumption, or activation of engine derate modes to prevent catastrophic overheating damage.

Common Symptoms

When fault code E45 is active, operators typically experience:

• Engine warning light or malfunction indicator lamp illuminated on the dashboard
• Engine operating in derate mode with reduced power output and limited RPM range
• Difficulty starting the engine, particularly in cold weather conditions
• Cooling fan running continuously at maximum speed regardless of actual engine temperature
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions

Potential Causes

The most common technical reasons for E45 appearing on used Liebherr excavators include:

• Coolant temperature sensor failure due to internal component degradation or contamination from coolant additives
• Damaged or corroded wiring harness connections at the sensor connector, particularly where harnesses route near the engine block or exhaust manifold
• Open or short circuit in the sensor wiring caused by harness chafing against frame components (common wear point near the engine mount brackets)
• Corroded or loose ground connections affecting sensor signal integrity
• Faulty ECM with internal circuit board damage (less common but possible in high-hour machines)
• Actual engine overheating conditions caused by cooling system failures (thermostat, water pump, or blocked radiator)

How to Troubleshoot and Fix Code E45

Step 1: Visual Inspection and Data Verification Connect Liebherr's LiDAT diagnostic software or a compatible diagnostic tool to retrieve active and stored fault codes. Record the freeze-frame data showing conditions when E45 was triggered. Perform a thorough visual inspection of the coolant temperature sensor (typically located on the engine block or cylinder head) and its wiring harness for obvious damage, corrosion, or coolant contamination on connectors.

Step 2: Electrical Testing Disconnect the coolant temperature sensor connector and measure resistance across the sensor terminals using a digital multimeter. At 68°F (20°C), most Liebherr sensors should read approximately 2,000-3,000 ohms (consult your specific service manual for exact specifications). Test the wiring harness for continuity from the sensor connector to the ECM and check for short circuits to ground. Inspect for voltage supply from the ECM (typically 5 volts reference signal).

Step 3: Component Replacement and System Verification For used excavators, carefully inspect connector pins for corrosion or "green crud" buildup—clean with electrical contact cleaner if necessary. Check harness routing for wear points where insulation may have rubbed through against engine components or frame members. Replace the coolant temperature sensor if resistance values are out of specification. After repairs, clear fault codes, operate the machine through a complete heat cycle, and verify E45 does not return.

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Disclaimer: This guide provides general troubleshooting information. Always consult your Liebherr service manual and consider professional diagnostic assistance for complex electrical issues or if you're uncertain about procedures. Improper repairs can cause additional damage to expensive electronic components.