What is Liebherr General Fault Code E36?

Fault Code E36 on Liebherr excavators indicates a malfunction in the hydraulic pump pressure sensor circuit or an abnormal pressure signal detected by the Electronic Control Module (ECM). This code typically points to issues with the pressure transducer that monitors main hydraulic system pressure, its wiring harness, or the ECM's ability to receive accurate pressure data.

This fault is critical for Liebherr machines because the hydraulic pump pressure sensor provides real-time feedback to the ECM, which regulates pump output, flow compensation, and load-sensing functions. When E36 triggers, the machine may enter a protective derate mode to prevent damage to hydraulic components. For used excavators, this code often surfaces due to sensor degradation, connector corrosion, or wiring damage from years of vibration and exposure to harsh operating conditions.

Common Symptoms

• Hydraulic system derate – Reduced swing speed, slower boom/arm movements, or limited digging force
• Warning light illuminated on the instrument cluster, often accompanied by an audible alarm
• Erratic hydraulic response – Inconsistent pump pressure causing jerky or unpredictable machine movements
• Error message displayed on the monitor screen specifically referencing hydraulic system or pressure sensor faults
• Machine may enter limp mode, restricting operations to basic functions only

Potential Causes

The most common technical reasons for Code E36 on used Liebherr excavators include:

• Failed hydraulic pressure sensor/transducer – Internal sensor element degradation due to age, contamination, or pressure spikes
• Damaged or corroded wiring harness – Particularly at connector points near the hydraulic pump where vibration and heat exposure are highest
• Loose or corroded electrical connectors – Moisture intrusion causing poor contact or short circuits
• Shorted or open circuit in the sensor signal wire between the transducer and ECM
• ECM internal fault – Less common, but possible in high-hour machines with electronic component wear
• Contaminated hydraulic oil causing sensor membrane damage or false readings

How to Troubleshoot and Fix Code E36

Step 1: Visual Inspection Begin by locating the hydraulic pump pressure sensor, typically mounted on or near the main hydraulic pump assembly. Inspect the wiring harness for obvious damage, abrasion points where wires contact the frame, or signs of rodent damage. On used excavators, check for oil contamination on connectors, which indicates seal failure.

Step 2: Electrical Testing Disconnect the pressure sensor connector and use a digital multimeter to check sensor resistance (typically 250-500 ohms depending on model specifications). Test for supply voltage at the connector (usually 5V reference from ECM) with ignition on. Check for continuity between sensor ground and chassis ground. Measure signal wire voltage while monitoring for fluctuations that indicate intermittent connection issues.

Step 3: Connector and Harness Examination Carefully inspect connector pins for corrosion, bent terminals, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease. Trace the harness back to the ECM, checking for rub points against hydraulic lines or structural members—common wear areas on older machines.

Step 4: Sensor Replacement and Calibration If electrical tests confirm sensor failure, replace with a genuine Liebherr pressure transducer to ensure proper calibration. After installation, use Liebherr diagnostic software (LiDat) to clear codes and verify live pressure readings match actual system pressure. Perform a hydraulic system pressure test to confirm proper operation.

Step 5: ECM Evaluation If the new sensor and verified wiring still trigger E36, the ECM may require inspection or replacement—consider professional ECM testing before replacement due to cost.

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Disclaimer: This guide provides general troubleshooting information. Always consult Liebherr service manuals specific to your machine model and serial number. For complex electrical or hydraulic repairs on used excavators, professional diagnostic services are recommended to prevent costly misdiagnosis.