What is Liebherr General Fault Code E112?

Fault Code E112 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading detected by the ECM (Engine Control Module). This diagnostic trouble code specifically signals that the electronic control system has identified either an electrical fault in the sensor wiring, a failed coolant temperature sensor, or temperature values that fall outside the manufacturer's programmed parameters.

In Liebherr excavators, the engine coolant temperature sensor plays a critical role in engine management by providing real-time data that influences fuel injection timing, idle speed control, and engine protection protocols. When E112 triggers, the ECM typically defaults to a preset temperature value, which can significantly impact engine performance, fuel efficiency, and may activate protective derate modes to prevent potential engine damage.

Common Symptoms

• Warning light illumination on the instrument cluster, often accompanied by a temperature gauge malfunction or erratic temperature readings
• Engine derate mode activation, limiting power output to protect components from potential overheating damage
• Rough idle or poor cold-start performance, as the ECM cannot accurately adjust fuel delivery based on actual engine temperature
• Increased fuel consumption due to the system operating on default temperature values rather than real-time data
• Check engine light remains illuminated continuously, with E112 stored in active or pending fault memory

Potential Causes

• Faulty coolant temperature sensor due to internal element degradation, common in machines with over 5,000 operating hours
• Damaged or corroded wiring harness at connector points, particularly where the harness routes near hot engine components or rubs against frame members
• Corroded electrical connectors at the sensor terminal, especially prevalent in excavators exposed to moisture, mud, or high-humidity environments
• Open or short circuit in the sensor signal wire between the sensor and ECM
• ECM internal fault (less common), where the temperature input circuit on the control module has failed
• Coolant contamination causing sensor element fouling or coating that affects accurate temperature readings

How to Troubleshoot and Fix Code E112

Step 1: Visual Inspection Begin by locating the engine coolant temperature sensor, typically installed in the engine block or cylinder head. Inspect the sensor connector for corrosion, moisture intrusion, or damaged pins. On used excavators, carefully trace the wiring harness back toward the ECM, checking for chafing, cracking, or evidence of previous repairs with electrical tape.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. Compare readings against Liebherr's specification chart (resistance varies with temperature—typically 2,000-3,000 ohms at 20°C). Check for continuity in the wiring between the sensor connector and ECM, and verify no shorts to ground using the ohmmeter function.

Step 3: Signal Voltage Verification With the ignition on and sensor disconnected, measure the reference voltage at the harness connector (should read approximately 5 volts). This confirms the ECM is supplying proper voltage. Reconnect the sensor and use Liebherr diagnostic software (LiDat or compatible scan tool) to monitor live coolant temperature data while comparing against an infrared thermometer reading of the actual engine temperature.

Step 4: Component Replacement and Verification If testing confirms sensor failure, replace with a genuine or OEM-equivalent coolant temperature sensor, applying dielectric grease to connector terminals to prevent future corrosion. For used machinery, always inspect the sensor mounting boss for thread damage or coolant leaks before installation. Clear fault codes, run the engine through a complete warm-up cycle, and verify E112 does not return.

Disclaimer: This guide provides general troubleshooting information for Liebherr excavators. Always consult the specific service manual for your machine model and consider engaging a certified Liebherr technician for complex electrical diagnostics or if you're unfamiliar with high-voltage systems and ECM programming procedures.