Komatsu PC130-6 Fault Code E108: Complete Technical Guide

What is Komatsu PC130-6 Fault Code E108?

Fault code E108 indicates a malfunction in the hydraulic pump discharge pressure sensor circuit. This sensor monitors the main hydraulic pump's discharge pressure and sends critical data to the Engine Control Module (ECM) to optimize engine load and fuel injection timing.

The PC130-6 relies on accurate pressure readings to balance engine performance with hydraulic demand. When this sensor circuit fails, the ECM cannot properly match engine output to hydraulic workload, resulting in reduced efficiency and potential component stress. This code is particularly critical because it directly affects the machine's ability to perform under varying load conditions.

Common Symptoms

• Warning lamp illuminated on the instrument panel with reduced hydraulic response
• Loss of digging force or slower cycle times, especially under heavy loads
• Engine over-revving during light hydraulic operations due to improper load sensing
• Intermittent power fluctuations when operating multiple hydraulic functions simultaneously
• Machine enters derate mode, limiting maximum engine RPM to protect components

Potential Causes

The most common causes for E108 on used PC130-6 excavators include:

• Damaged pressure sensor wiring harness near the main pump area where vibration and hydraulic hose movement cause conductor breakage
• Corroded or oil-contaminated sensor connector (3-pin connector located on pump housing)
• Failed pressure sensor due to internal diaphragm rupture or electronic component degradation
• Faulty ECM ground connections at chassis mounting points, common in machines with 5,000+ operating hours
• Hydraulic oil contamination affecting sensor accuracy through deposit buildup on sensor element

How to Troubleshoot and Fix Code E108

Step 1: Visual Inspection Locate the discharge pressure sensor on the main hydraulic pump housing. Inspect the wiring harness for abrasion points where it contacts the pump body or nearby hoses. Check the connector for oil intrusion, corrosion, or damaged pins. On used excavators, this harness frequently rubs against mounting brackets.

Step 2: Electrical Testing Using a digital multimeter, check sensor supply voltage at the connector (should read 4.8-5.2V with ignition on). Test sensor signal wire resistance to ground (should be 10-15kΩ at 20°C). Verify ECM ground circuit resistance is below 1Ω.

Step 3: Sensor Performance Check Connect Komatsu diagnostic software (KOMTRAX or compatible scan tool) to monitor live pressure readings. Compare against mechanical gauge readings. Replace sensor if variance exceeds 10%. Before replacing components on used machines, clean all connectors with electrical contact cleaner and check for harness chafing repairs.

Disclaimer: This guide provides general troubleshooting information. Always consult Komatsu service manuals and qualified technicians for definitive diagnosis and repair procedures specific to your machine's configuration.