What is Komatsu PC110-8M0 Fault Code E-8?

Fault Code E-8 on the Komatsu PC110-8M0 indicates a hydraulic oil temperature sensor malfunction or abnormally high hydraulic oil temperature. This code is generated when the machine's Electronic Control Module (ECM) detects either a sensor circuit failure or oil temperatures exceeding safe operating limits (typically above 90-95°C/194-203°F).

The PC110-8M0's hydraulic system relies on precise temperature monitoring to protect critical components like the hydraulic pump, control valves, and cylinder seals. When hydraulic oil overheats or the sensor fails, the system cannot properly regulate cooling functions, potentially leading to accelerated component wear, seal deterioration, and catastrophic pump failure. For used excavators, this code often signals degraded cooling capacity or sensor wear that requires immediate attention.

Common Symptoms

When Code E-8 is active, operators typically experience:

• Warning light illumination on the instrument cluster (hydraulic temperature warning or check engine light)
• Reduced hydraulic performance including slow cycle times and weak implement movements
• Machine derate mode where engine power is automatically limited to prevent damage
• Audible warning alarms from the cab when temperature thresholds are exceeded
• Visible steam or heat radiating from the hydraulic tank area during operation

Potential Causes

The most common technical causes for E-8 on used PC110-8M0 excavators include:

• Faulty hydraulic oil temperature sensor – thermal cycling and age cause sensor drift or open circuits
• Damaged sensor wiring harness – known rub points near the hydraulic tank and along frame rails cause shorts or breaks
• Plugged hydraulic oil cooler – debris, mud, and environmental contamination restrict airflow
• Low coolant level in cooling system – affects heat exchanger efficiency for oil cooling
• Degraded hydraulic oil – contaminated or breakdown oil loses heat transfer properties
• Failed cooling fan or thermostat – prevents adequate heat dissipation from the system
• Corroded electrical connectors – common in used machines exposed to moisture and jobsite conditions

How to Troubleshoot and Fix Code E-8

Step 1: Initial Inspection and Data Verification Connect Komatsu diagnostic software (KOMTRAX Plus or PC Service Tool) to verify active and stored codes. Check live data to determine actual hydraulic oil temperature versus sensor reading. Inspect the hydraulic oil level, color, and condition – contaminated or low oil exacerbates temperature issues.

Step 2: Sensor Circuit Testing Locate the hydraulic oil temperature sensor (typically mounted on the hydraulic tank). Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture intrusion – extremely common on used excavators. Using a digital multimeter, measure sensor resistance at ambient temperature (should read approximately 2,000-3,000 ohms at 20°C). Compare readings against Komatsu specifications. Check for continuity in the wiring harness from sensor to ECM, focusing on known wear points.

Step 3: Physical System Inspection If sensor tests pass, inspect the hydraulic oil cooler for blockages – remove debris and pressure-wash if necessary. Check cooling fan operation and belt tension. Verify coolant level in the radiator and inspect for leaks. For used machines, examine harness routing for chafing against frame members and verify all ground connections are clean and tight.

Step 4: Component Replacement and Verification Replace the temperature sensor if resistance values are out of specification or if physical damage is evident. Use genuine Komatsu parts (part number specific to PC110-8M0) to ensure accuracy. After repairs, clear codes, run the machine through normal operating cycles, and monitor temperature data to confirm proper operation.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and seek professional assistance from certified technicians for complex hydraulic or electrical diagnostics.