What is Komatsu PC210LC-8 Fault Code E15 CA731?

Fault Code E15 CA731 indicates a communication error between the machine's Engine Control Module (ECM) and the Hydraulic Control Module (HCM) on the Komatsu PC210LC-8 excavator. This diagnostic trouble code (DTC) specifically signals that the CAN bus communication line has detected an intermittent or complete loss of data transmission between these two critical control systems.

The Komatsu PC210LC-8 relies on continuous data exchange between the ECM and HCM to synchronize engine performance with hydraulic demand. When communication breaks down, the machine cannot properly coordinate engine speed, fuel delivery, and hydraulic flow—directly impacting productivity and potentially causing unexpected machine behavior. This code is particularly common in used excavators where wiring harnesses have experienced years of vibration, temperature cycling, and physical stress.

Common Symptoms

When Code E15 CA731 is active, operators typically experience:

• Machine enters derated mode with significantly reduced hydraulic power and engine RPM limitation
• Intermittent loss of hydraulic functions or sluggish response from boom, arm, or bucket controls
• Dashboard warning lights illuminate, including the malfunction indicator lamp and possible hydraulic system alerts
• Engine may run rough or fail to respond properly to throttle inputs during hydraulic operations
• Communication error messages displayed on the monitor panel, sometimes appearing intermittently before becoming constant

Potential Causes

The most common technical causes for this fault code on used PC210LC-8 machines include:

• Damaged or corroded CAN bus wiring harness between ECM and HCM, especially at flex points near the swing bearing or along the boom base
• Loose or corroded electrical connectors at either control module, often caused by moisture intrusion in older machines
• Failed termination resistor on the CAN bus network (typically 120-ohm resistor at network endpoints)
• ECM or HCM internal failure, though less common than wiring issues
• Voltage supply problems to either module caused by failing relays, poor grounds, or battery connection issues
• Physical damage to wiring from rubbing against frame members—a known wear point on PC210LC models near the right-hand side main harness routing

How to Troubleshoot and Fix Code E15 CA731

Step 1: Visual Inspection of Wiring and Connectors

Begin with a thorough physical examination of the CAN bus harness running between the ECM (located behind the right-hand side panel) and the HCM (mounted near the hydraulic pump). On used excavators, pay special attention to harness routing near the swing bearing and boom pivot points where vibration causes wire chafing. Disconnect all related connectors and inspect for corrosion, bent pins, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease before reconnection.

Step 2: Test CAN Bus Continuity and Resistance

Using a digital multimeter, measure resistance between the CAN-H and CAN-L lines at both the ECM and HCM connectors (consult the PC210LC-8 service manual for specific pin locations). You should measure approximately 60 ohms with both modules connected, indicating proper termination resistors. Check for continuity on each individual wire—any open circuit indicates a break in the harness that requires repair or replacement.

Step 3: Verify Power Supply and Ground Circuits

Measure voltage supply to both modules with ignition ON—should read battery voltage (typically 24V on this model). Check ground circuits for resistance; any reading above 0.5 ohms indicates a poor ground connection. For used machines, remove ground connection points, clean contact surfaces thoroughly with a wire brush, and apply anti-corrosion compound.

Step 4: Perform Diagnostic Software Testing

Connect Komatsu KOMTRAX or compatible diagnostic software to verify real-time communication status between modules. Monitor data transmission rates and look for intermittent dropouts. If wiring and connections test good but communication still fails, perform a module relearn procedure or consider ECM/HCM replacement—though hardware failure is rare compared to wiring issues on used equipment.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs can cause additional damage or safety hazards.