Komatsu PC650-8R Fault Code E-24: Complete Diagnostic Guide

What is Komatsu PC650-8R Fault Code E-24?

Fault Code E-24 on the Komatsu PC650-8R indicates a malfunction in the hydraulic oil temperature sensor circuit or an abnormal temperature reading in the hydraulic system. This code is triggered when the Electronic Control Module (ECM) detects either an open circuit, short circuit, or an out-of-range signal from the hydraulic oil temperature sensor.

This fault is critical for the PC650-8R's performance because the hydraulic system operates within specific temperature parameters. The ECM uses temperature data to regulate hydraulic pump output, protect system components from thermal damage, and prevent viscosity-related performance issues. When E-24 is active, the machine may enter a protective derate mode to prevent catastrophic hydraulic system failure.

Common Symptoms

When Code E-24 is active on your PC650-8R, operators typically experience:

• Warning light illuminated on the monitor panel with E-24 displayed
• Reduced hydraulic performance or sluggish operation of boom, arm, and bucket functions
• Automatic engine derate limiting RPM to protect the hydraulic system
• Inaccurate hydraulic oil temperature readings on the display (showing extremely high or low values)
• Intermittent fault activation, especially during cold starts or after extended operation

Potential Causes

The most common technical causes for E-24 on used PC650-8R excavators include:

• Hydraulic oil temperature sensor failure due to age, thermal cycling, or internal component degradation
• Damaged wiring harness near the hydraulic tank, particularly at rub points where the harness contacts frame members
• Corroded or loose connector pins at the sensor or ECM connection points (common in machines exposed to moisture)
• Short circuit to ground caused by abraded insulation on sensor wiring
• ECM internal fault (rare, but possible in high-hour machines)
• Contaminated hydraulic oil affecting sensor accuracy

How to Troubleshoot and Fix Code E-24

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor on the hydraulic tank. Inspect the wiring harness from sensor to ECM for visible damage, abrasion, or oil contamination. Check the connector for corrosion, bent pins, or moisture intrusion—critical on used excavators with high operating hours.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance at various temperatures (consult Komatsu specifications, typically 200-400 ohms at 20°C). Check for continuity in the wiring harness and verify no short to ground exists. Measure supply voltage at the sensor connector (should be approximately 5V reference voltage from ECM).

Step 3: Component Replacement and Verification If sensor resistance is out of specification or wiring shows damage, replace the faulty component. For used excavators, always apply dielectric grease to connectors to prevent future corrosion. Clear the fault code using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then operate the machine through a full temperature cycle to verify repair.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific serial number and consider professional technician assistance for complex electrical diagnostics or ECM-related issues.