What is Liebherr General Fault Code E46?

Liebherr Fault Code E46 indicates a malfunction in the pilot pressure sensor circuit or an abnormal pilot pressure reading in the hydraulic control system. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects voltage readings outside the normal operating range from the pilot pressure sensor, typically between 0.5-4.5 volts.

The pilot pressure system is critical for Liebherr excavators as it controls the proportional hydraulic functions for all joystick and pedal operations. When E46 appears, the ECM may limit machine functions to protect hydraulic components from damage due to incorrect pressure readings. This sensor monitors the pressure generated by the pilot pump, which translates operator inputs into precise hydraulic movements. Any disruption to this signal compromises the excavator's controllability and operational safety.

Common Symptoms

• Erratic or unresponsive joystick controls with delayed or inconsistent hydraulic response to operator inputs
• Warning light illumination on the instrument cluster, often accompanied by an audible alarm
• Reduced hydraulic function speed or complete loss of certain movements (boom, arm, bucket, or swing)
• Intermittent control issues that worsen when the machine warms up or during high-demand operations
• Engine derate mode activation in some Liebherr models, limiting RPM to protect the system

Potential Causes

The most common technical causes for Code E46 on used Liebherr excavators include:

• Pilot pressure sensor failure due to internal component wear, contamination, or diaphragm rupture
• Wiring harness damage at known rub points near the main control valve or along the right-hand chassis rail where cables contact the frame
• Corroded or loose electrical connectors at the sensor terminal, especially on machines with high hour counts or exposure to moisture
• Low pilot pressure caused by a worn pilot pump, clogged pilot filter, or internal leakage in the pilot circuit
• ECM voltage supply issues including damaged pins or poor ground connections at the controller
• Hydraulic oil contamination affecting sensor accuracy and causing false readings

How to Troubleshoot and Fix Code E46

Step 1: Visual Inspection and Connector Check Begin by locating the pilot pressure sensor mounted on the main control valve block. Inspect the wiring harness for abrasion, cuts, or contact with hot surfaces. On used excavators, pay particular attention to areas where the harness passes through bulkheads or near moving components. Disconnect the sensor connector and examine pins for corrosion, bent contacts, or hydraulic oil intrusion. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, perform a voltage supply check at the sensor connector with the key on, engine off. You should read approximately 5 volts on the supply wire. Check ground continuity to ensure less than 1 ohm resistance to chassis ground. With the sensor connected and engine running at idle, backprobe the signal wire—normal readings range from 0.8-1.5 volts at idle pilot pressure. Readings outside this range indicate sensor failure or circuit issues.

Step 3: Pilot Pressure System Verification Install a hydraulic pressure gauge (0-1000 PSI range) at the pilot test port on the control valve. Normal pilot pressure should read 350-550 PSI depending on model specifications. Low readings point to pilot pump wear, restricted pilot filter, or relief valve problems rather than sensor issues. On used machines, always replace the pilot filter before condemning the pump.

Step 4: Sensor Replacement and Calibration If electrical tests confirm sensor failure, replace with a genuine Liebherr pilot pressure sensor using the correct torque specification (typically 15-20 Nm). After installation, clear fault codes using Liebherr LiDat diagnostic software or compatible scan tool. Perform a sensor calibration procedure if required by your specific model. Test all hydraulic functions under load before returning the machine to service.

Important for Used Equipment: Before replacing expensive components, thoroughly inspect all harness routing and connections. Many E46 codes on high-hour machines result from connector corrosion or wire chafing rather than actual sensor failure, potentially saving hundreds in unnecessary parts costs.

---

Disclaimer: This guide provides general troubleshooting information for Liebherr excavators. Always consult the official service manual for your specific model and serial number. If you lack proper diagnostic tools or hydraulic system experience, contact a certified Liebherr technician to prevent injury or further equipment damage.