What is Liebherr Excavator Fault Code E087?

Fault Code E087 on Liebherr excavators indicates a malfunction in the Engine Oil Pressure Sensor Circuit or abnormally low engine oil pressure detected by the Electronic Control Module (ECM). This diagnostic trouble code (DTC) signals that the oil pressure sensor is either sending an out-of-range signal to the ECM, or the actual oil pressure has dropped below the manufacturer's minimum threshold during operation.

In Liebherr's diesel engine management systems, maintaining proper oil pressure is critical for lubricating high-stress components like crankshaft bearings, camshaft lobes, and turbocharger assemblies. When Code E087 triggers, the ECM may initiate protective measures to prevent catastrophic engine damage. For used excavators, this code often appears due to sensor degradation, wiring issues from years of vibration exposure, or actual mechanical oil pressure loss from worn internal components.

Common Symptoms

• Red oil pressure warning light illuminated on the instrument cluster, often accompanied by an audible alarm
• Engine derate mode activated, limiting RPM and hydraulic performance to protect the engine from damage
• Rough idle or intermittent stalling, especially when the machine is hot or under load
• Fluctuating oil pressure gauge readings or gauge stuck at zero despite the engine running normally
• ECM-triggered engine shutdown in severe cases where critically low pressure is detected

Potential Causes

The most common technical reasons for E087 on used Liebherr excavators include:

• Failed or contaminated oil pressure sensor – Internal diaphragm failure or debris buildup affects signal accuracy
• Damaged wiring harness or corroded connectors at the sensor plug, particularly where the harness rubs against engine mounts or frame rails (known wear point on older units)
• Low engine oil level due to leaks, consumption, or inadequate maintenance
• Worn oil pump or clogged oil filter restricting flow and reducing actual pressure
• Faulty ECM ground connection causing erratic sensor readings
• Incorrect oil viscosity for operating temperature range, common in machines with unknown service history

How to Troubleshoot and Fix Code E087

Step 1: Visual Inspection and Oil Level Check Begin by verifying the engine oil level using the dipstick with the machine on level ground. Top off if low and inspect for external leaks around the oil pan, filter housing, and turbo oil lines. On used excavators, check the oil condition – metallic particles or milky appearance indicate serious internal wear.

Step 2: Inspect Oil Pressure Sensor and Wiring Locate the oil pressure sensor (typically mounted on the engine block near the oil filter). Disconnect the electrical connector and inspect for corrosion, moisture intrusion, or bent pins. Trace the wiring harness back to the ECM, checking for chafing at known rub points against the engine block or frame. Use a multimeter to check for continuity in the wiring and verify the ground circuit has less than 0.5 ohms resistance.

Step 3: Test Sensor Output and Actual Oil Pressure With the sensor disconnected, measure its resistance (typically 50-200 ohms at room temperature for most Liebherr sensors – verify in your service manual). Install a mechanical oil pressure gauge at the sensor port and run the engine to verify actual oil pressure meets specifications (usually 40-60 PSI at operating temperature). If mechanical pressure is correct but the sensor reads incorrectly, replace the oil pressure sensor with an OEM or equivalent part.

Step 4: Advanced Diagnostics If the sensor and wiring test good, connect Liebherr LiDat diagnostic software or compatible scan tool to read live data and freeze frame information. Monitor oil pressure values during idle, acceleration, and under load. Check for related codes that might indicate ECM issues or other engine problems. For persistent issues on used machines, consider inspecting the oil pump pickup screen for blockage and testing oil pump output pressure.

Critical Note for Used Equipment: Before replacing expensive components, thoroughly inspect all electrical connectors for the green corrosion typical in aged machines, and check that previous owners haven't installed incorrect sensors or modified wiring. Many E087 codes on older Liebherr excavators resolve with proper connector cleaning and harness rerouting.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Liebherr service manual for your specific model and serial number. If you lack proper diagnostic tools or experience with high-pressure lubrication systems, consult a certified Liebherr technician to avoid engine damage or personal injury.