Komatsu PC800-8R Fault Code H-13: Complete Diagnostic Guide

What is Komatsu PC800-8R Fault Code H-13?

Fault Code H-13 on the Komatsu PC800-8R 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 PC800-8R'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:

• Warning light illumination on the monitor panel, often accompanied by an audible alarm
• Hydraulic system derate or reduced hydraulic flow to prevent potential overheating damage
• Inaccurate temperature gauge readings showing either extremely high or low temperatures
• Intermittent code activation during machine warm-up or under heavy load conditions
• Sluggish hydraulic response as the ECM limits system performance based on faulty sensor data

Potential Causes

The most common technical causes for H-13 on used PC800-8R excavators include:

• Sensor failure due to age, thermal cycling, or internal component degradation
• Wiring harness damage at known rub points near the hydraulic tank or along the chassis frame
• Corroded or loose connector pins at the sensor connection point, especially on machines operating in wet or corrosive environments
• Damaged sensor threads or improper installation causing poor thermal contact with hydraulic fluid
• ECM internal fault (rare) affecting the sensor input circuit
• Hydraulic oil contamination causing sensor element fouling or coating

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 for obvious damage, chafing, or oil contamination. Check connector pins for corrosion, bent terminals, or moisture intrusion—common issues in used excavators.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance at ambient temperature (typically 2,000-3,000 ohms at 20°C, but verify against Komatsu specifications). Check for continuity in the wiring harness from sensor to ECM. Measure voltage supply at the connector (usually 5V reference voltage from ECM).

Step 3: Sensor Replacement and Verification If resistance values are out of specification or the harness shows damage, replace the faulty component. For used machines, always apply dielectric grease to connector pins to prevent future corrosion. Clear the code using Komatsu diagnostic software (KOMTRAX) and monitor during a full operational cycle.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual and consider professional diagnostic assistance for complex electrical issues or if you lack proper diagnostic equipment.