Komatsu PC800SE-7 Fault Code H-13: Complete Diagnostic Guide

What is Komatsu PC800SE-7 Fault Code H-13?

Fault Code H-13 indicates a hydraulic oil temperature sensor circuit malfunction in the Komatsu PC800SE-7 excavator. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage signal from the hydraulic oil temperature sensor, typically indicating an open circuit, short circuit, or sensor failure.

The hydraulic oil temperature sensor plays a critical role in monitoring the operating temperature of the hydraulic system. When hydraulic oil exceeds safe operating temperatures, the system can experience accelerated component wear, seal degradation, and reduced hydraulic efficiency. For a large excavator like the PC800SE-7, maintaining proper hydraulic temperature monitoring is essential for protecting expensive pumps, motors, and control valves from thermal damage.

Common Symptoms

When Code H-13 is active, operators typically experience:

• Warning light illuminated on the instrument cluster, specifically the hydraulic temperature indicator
• Erratic or absent hydraulic temperature readings on the monitor display (may show dashes or default values)
• Potential machine derate or reduced hydraulic performance in some operating modes
• Audible warning alarm when the code first triggers
• Loss of automatic cooling fan control based on hydraulic temperature

Potential Causes

The most common technical causes for H-13 on used PC800SE-7 excavators include:

• Failed hydraulic oil temperature sensor due to age, thermal cycling, or internal element degradation
• Damaged or corroded wiring harness between the sensor and ECM, particularly at connection points near the hydraulic tank
• Loose or corroded electrical connectors at the sensor or ECM interface
• Chafed wiring where the harness routes near moving components or sharp edges (common wear point on older machines)
• ECM internal circuit failure (rare, but possible on high-hour machines)
• Water intrusion into sensor connector causing intermittent short circuits

How to Troubleshoot and Fix Code H-13

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor (typically mounted on the hydraulic tank). Inspect the sensor connector for corrosion, oil contamination, or damaged pins. On used excavators, check the entire wiring harness routing for signs of chafing, especially where it passes through bulkheads or near hydraulic lines.

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 from sensor to ECM. Measure voltage supply at the sensor connector with ignition on (should be approximately 5V reference voltage).

Step 3: Component Replacement and Verification If the sensor tests out of specification or wiring shows damage, replace the faulty component. For used machines, 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 the 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.