What is Komatsu PC110-7 Fault Code E-24?

Fault Code E-24 on the Komatsu PC110-7 excavator indicates a malfunction in the hydraulic oil temperature sensor circuit. This code triggers when the Engine Control Module (ECM) detects an abnormal voltage signal from the temperature sensor monitoring the hydraulic oil temperature in the main hydraulic system.

The hydraulic oil temperature sensor plays a critical role in protecting the PC110-7's hydraulic system from damage due to overheating. When hydraulic fluid exceeds safe operating temperatures (typically above 110-120°C or 230-248°F), oil viscosity breaks down, accelerating wear on pumps, motors, and control valves. The ECM relies on accurate temperature readings to alert operators and potentially initiate protective measures. In used excavators, this sensor circuit commonly fails due to connector corrosion, wiring degradation, or sensor element deterioration from prolonged heat exposure.

Common Symptoms

When Code E-24 is active on your PC110-7, you may experience:

• Hydraulic temperature warning light illuminated on the instrument cluster (typically an orange/amber icon)
• Intermittent or constant code display on the monitor panel, even when hydraulic oil temperature feels normal to the touch on the reservoir
• False overheating alarms during cold starts or normal operating conditions
• Loss of temperature gauge reading on the display, showing dashes or erratic readings
• Potential automatic derate or reduced engine RPM if the ECM interprets the fault as a critical overheat condition (model-year dependent)

Potential Causes

The most common technical causes for E-24 on used PC110-7 excavators include:

• Damaged or corroded sensor connector at the hydraulic tank—this model is known for connector exposure to moisture and debris
• Failed hydraulic oil temperature sensor—internal thermistor element degradation after 5,000+ operating hours
• Broken or shorted sensor wiring harness—particularly at routing points near the hydraulic tank mounting bracket where vibration causes wire chafing
• Poor ground connection at the sensor or ECM chassis ground points
• ECM internal circuit failure (rare, but possible in high-hour machines)
• Contaminated connector terminals from hydraulic oil seepage or environmental exposure

How to Troubleshoot and Fix Code E-24

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor on the main hydraulic tank (typically on the tank side or return line). Inspect the wiring harness and connector for obvious damage, oil contamination, corrosion (green/white oxidation), or loose pins. On used PC110-7s, check for wire insulation cracks at the harness bend radius near the tank bracket—a known wear point.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to check sensor resistance. At room temperature (20°C/68°F), resistance should typically read between 2,000-3,000 ohms (consult your specific service manual for exact specifications). If the reading shows infinite resistance (open circuit) or near-zero ohms (short circuit), replace the sensor. Also check for voltage supply from the ECM harness side—you should see approximately 5 volts DC on the signal wire with ignition on.

Step 3: Harness and Ground Verification Trace the sensor wiring back to the ECM connector, checking for continuity and shorts to ground using your multimeter's continuity function. Pay special attention to harness routing points where cables pass through metal brackets or near moving components. Clean all ground connection points with electrical contact cleaner and verify tight connections. For used excavators, corrosion at ground terminals is a frequent culprit.

Step 4: Advanced Diagnostics If sensor and wiring test normal, connect Komatsu diagnostic software (KOMTRAX or PC-based service tool) to read live sensor voltage data. Compare actual hydraulic oil temperature (use an infrared thermometer on the tank) with ECM readings. A significant variance indicates ECM processing issues or calibration drift.

Disclaimer: This guide provides general troubleshooting information for the Komatsu PC110-7. Always consult the manufacturer's official service manual for specifications and procedures. If you're uncomfortable performing electrical diagnostics, contact a certified Komatsu technician or qualified heavy equipment mechanic to prevent further damage to your machine.