Komatsu PC800-7 Fault Code H-13: Complete Diagnostic Guide

What is Komatsu PC800-7 Fault Code H-13?

Fault Code H-13 on the Komatsu PC800-7 indicates a hydraulic oil temperature sensor circuit malfunction or abnormal high-temperature reading in the hydraulic system. This code is triggered when the Electronic Control Module (ECM) detects either an open circuit, short circuit, or out-of-range signal from the hydraulic oil temperature sensor.

The hydraulic oil temperature sensor is critical for the PC800-7's performance management system. It monitors hydraulic fluid temperature to prevent overheating, which can cause accelerated component wear, seal degradation, and catastrophic hydraulic pump failure. When this sensor malfunctions, the machine may enter a protective derate mode or display inaccurate temperature readings, compromising operational efficiency and potentially causing expensive damage.

Common Symptoms

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

• Hydraulic oil temperature warning light illuminated on the instrument panel
• Reduced engine power or hydraulic flow as the system enters protective derate mode
• Inaccurate or erratic temperature gauge readings (showing extremely high or low values)
• Intermittent alarm activation even when hydraulic oil feels cool to touch
• Machine may refuse to operate at full capacity or enter limp mode during startup

Potential Causes

The most common technical reasons for H-13 on used PC800-7 excavators include:

• Faulty hydraulic oil temperature sensor due to age-related degradation or thermal cycling damage
• Damaged wiring harness near the hydraulic tank, especially at known rub points where the harness contacts frame members
• Corroded or loose connector pins at the sensor plug, common in machines exposed to moisture or harsh environments
• ECM internal fault or corrupted calibration data (less common but possible in high-hour machines)
• Actual hydraulic system overheating causing legitimate high-temperature readings
• Broken or frayed ground wire affecting sensor circuit integrity

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 wiring harness from sensor to ECM for visible damage, chafing, or oil contamination. On used excavators, pay special attention to harness routing near moving components and check all connector pins for corrosion or bent terminals.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance at various temperatures (consult Komatsu service manual for specific resistance values—typically 200-400 ohms at 20°C). Check for continuity in the wiring harness and verify supply voltage (usually 5V reference) at the sensor connector with ignition on.

Step 3: Sensor and Circuit Verification If resistance values are out of specification, replace the temperature sensor (Komatsu part number specific to PC800-7). If wiring shows damage, repair or replace the affected harness section, ensuring proper heat-shrink sealing and secure routing away from friction points. Clear the code using Komatsu diagnostic software (KOMTRAX) and monitor for recurrence.

Step 4: Advanced Diagnostics If the code persists after sensor replacement, test ECM input voltage and inspect for internal ECM damage. For used machines with high hours, consider checking actual hydraulic oil temperature with an infrared thermometer to rule out genuine overheating issues.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC800-7 service manual and consider professional assistance from certified Komatsu technicians for complex electrical diagnostics or ECM programming.