Komatsu PC210LC-8 Fault Code H-5: Technical Guide

What is Komatsu PC210LC-8 Fault Code H-5?

Fault Code H-5 on the Komatsu PC210LC-8 indicates a hydraulic pump discharge pressure sensor malfunction or abnormal pressure detection. This code specifically relates to the main hydraulic pump's pressure monitoring system, which is critical for the excavator's load-sensing hydraulic circuit.

The pressure sensor sends voltage signals to the Engine Control Module (ECM) and Hydraulic Control Unit, allowing the machine to adjust pump output based on workload demands. When this sensor fails or reads outside normal parameters (typically 0-400 bar), the system triggers H-5 to protect hydraulic components from damage. For the PC210LC-8's advanced hydraulic management system, accurate pressure feedback is essential for fuel efficiency, precise control, and preventing catastrophic pump failure.

Common Symptoms

When Code H-5 is active, operators typically experience:

• Warning light illumination on the monitor panel with reduced machine responsiveness
• Sluggish or erratic hydraulic functions, particularly during combined operations (boom + swing)
• Automatic engine derate to limit hydraulic demand and protect the system
• Intermittent power loss during high-pressure tasks like digging or lifting
• Fluctuating hydraulic flow causing jerky movements in boom, arm, or bucket circuits

Potential Causes

The most common technical failures triggering H-5 on used PC210LC-8 excavators include:

• Pressure sensor degradation from contaminated hydraulic oil causing internal diaphragm failure
• Wiring harness damage at known friction points near the pump mounting bracket or along the main chassis rail
• Corroded or loose electrical connectors at the sensor or ECM interface (especially on machines with 5,000+ operating hours)
• Voltage supply issues from damaged pin terminals or compromised ground connections
• Hydraulic oil contamination affecting sensor accuracy through particulate buildup
• ECM calibration drift or software corruption in older control units

How to Troubleshoot and Fix Code H-5

Step 1: Visual Inspection Check the pressure sensor (located on the main pump discharge port) for physical damage, oil leaks, or loose mounting. Inspect the wiring harness for abrasion, especially where it routes against the pump case—a common wear point on used machines.

Step 2: Electrical Testing Using a digital multimeter, verify the sensor receives proper supply voltage (typically 5V DC) from the ECM. Check signal wire continuity and measure resistance at the sensor connector (should read 100-500 ohms depending on temperature). Inspect connector pins for corrosion—clean with electrical contact cleaner if needed.

Step 3: Hydraulic System Check Test actual hydraulic pressure using a calibrated pressure gauge at the test port. Compare readings with sensor output voltage (consult Komatsu service manual specs). If pressure reads normal but sensor output is erratic, replace the pressure sensor (Komatsu part 7861-93-1650 or equivalent).

Step 4: Advanced Diagnostics Connect Komatsu diagnostic software (KOMTRAX Plus) to read live sensor data and perform active tests. For used excavators, always inspect hydraulic filter condition and oil contamination levels—degraded oil accelerates sensor failure.

Disclaimer: This guide provides general troubleshooting steps. Always consult the official Komatsu service manual for your specific machine serial number. Complex hydraulic and electrical repairs should be performed by certified technicians with proper diagnostic equipment.