What is Liebherr General Fault Code E137?

Fault Code E137 indicates a malfunction in the engine coolant temperature sensor circuit or an implausible coolant temperature reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects voltage signals outside the normal operating range from the coolant temperature sensor (CTS), or when the sensor reading doesn't correlate with actual engine operating conditions.

The coolant temperature sensor is critical for Liebherr excavators because it directly influences fuel injection timing, engine warm-up cycles, and hydraulic oil temperature management. When E137 activates, the ECM may default to a predetermined temperature value, potentially causing inefficient combustion, increased emissions, and reduced hydraulic system performance. In used excavators, this code often appears due to sensor degradation or harness deterioration rather than actual overheating issues.

Common Symptoms

• Engine warning light illuminated on the instrument cluster with possible derate mode activation
• Hard starting or rough idle, especially during cold starts when the ECM relies heavily on temperature data
• Excessive black smoke from exhaust due to improper fuel mapping
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Hydraulic system sluggishness during initial operation as the system fails to recognize proper warm-up status

Potential Causes

The most common technical causes for E137 in used Liebherr excavators include:

• Coolant temperature sensor failure due to internal resistance drift or element contamination from degraded coolant
• Wiring harness damage at known friction points near the engine block mounting brackets or along the frame rail
• Corroded or moisture-infiltrated connectors at the sensor or ECM interface, particularly common in machines operating in wet environments
• ECM software calibration issues following previous repairs or component replacements without proper parameter updates
• Faulty ECM ground connections causing erratic voltage reference signals
• Coolant system air pockets creating actual temperature inconsistencies that trigger implausible reading detection

How to Troubleshoot and Fix Code E137

Step 1: Visual Inspection and Data Verification Begin by connecting Liebherr diagnostic software (LiDat or equivalent) to retrieve freeze frame data and confirm actual coolant temperature versus sensor reading. Visually inspect the coolant temperature sensor (typically located on the engine block near the thermostat housing) and its wiring harness for physical damage, corrosion, or coolant leaks. On used excavators, pay special attention to harness routing where it contacts metal edges or moving components.

Step 2: Electrical Testing Disconnect the coolant temperature sensor connector and measure resistance across the sensor terminals using a digital multimeter. Compare readings against Liebherr specifications (typically 2,000-3,000 ohms at 20°C, decreasing as temperature rises). Check voltage supply at the harness connector with ignition on—should read approximately 5 volts reference voltage from the ECM. Inspect connector pins for corrosion or bent terminals that compromise connection integrity.

Step 3: Circuit and Component Replacement Test continuity of the sensor signal wire and ground wire back to the ECM, checking for shorts to power or ground. If resistance and voltage tests pass but the code persists, replace the coolant temperature sensor with a genuine Liebherr part and clear codes. For used machines, consider replacing the connector pigtail simultaneously, as internal corrosion often isn't visible. After replacement, perform a complete coolant system purge to eliminate air pockets, then verify proper ECM recognition through diagnostic software.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Liebherr service manual for your specific model and serial number. Complex electrical diagnostics should be performed by qualified technicians with proper diagnostic equipment.