Komatsu PC110-7 Fault Code H-13: Complete Diagnostic Guide

What is Komatsu PC110-7 Fault Code H-13?

Fault Code H-13 on the Komatsu PC110-7 indicates a hydraulic oil temperature sensor abnormality or circuit malfunction. This code triggers when the ECM (Engine Control Module) detects an unusually high voltage reading, an open circuit, or irregular signals from the hydraulic oil temperature sensor located in the main hydraulic pump assembly.

This sensor is critical for the PC110-7's performance because it monitors the operating temperature of the hydraulic oil and prevents overheating that could damage pumps, motors, and seals. When the ECM cannot accurately read hydraulic temperatures, it may initiate protective derate modes or warning protocols to prevent catastrophic hydraulic system failure.

Common Symptoms

When fault code H-13 is active, operators typically experience:

• Hydraulic oil temperature warning light illuminated on the instrument panel
• Reduced hydraulic power or sluggish response in boom, arm, and bucket controls
• Erratic temperature gauge readings or gauge remaining at minimum/maximum positions
• Engine derating or limited RPM to protect hydraulic components
• Intermittent warning that appears during warm-up or after extended operation

Potential Causes

The most common technical causes for H-13 on used PC110-7 excavators include:

• Failed hydraulic oil temperature sensor due to internal resistance drift (common in machines with 5,000+ hours)
• Damaged or corroded wiring harness near the hydraulic pump housing where vibration and heat cause insulation breakdown
• Loose or oxidized connector pins at the sensor plug (especially in machines exposed to moisture or extreme conditions)
• Open circuit or short to ground in the signal wire between the sensor and ECM
• ECM malfunction (rare, but possible in high-hour machines with electrical system degradation)

How to Troubleshoot and Fix Code H-13

Step 1: Visual Inspection Locate the hydraulic oil temperature sensor on the main hydraulic pump assembly. Inspect the wiring harness for visible damage, particularly where it routes near moving components or hot surfaces. Check the connector for corrosion, bent pins, or oil contamination—common in used excavators.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. At room temperature (68°F/20°C), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Check for continuity in the wiring from sensor to ECM, and verify there's no short to ground.

Step 3: Signal Voltage Check With the sensor connected and ignition on (engine off), back-probe the signal wire at the ECM connector. You should read approximately 5V reference voltage. A reading of 0V or 5V constant indicates a circuit fault rather than sensor failure.

Step 4: Component Replacement For used excavators, if wiring and connectors appear worn, replace the entire sensor-to-ECM harness section rather than just the sensor. This prevents recurring codes from hidden harness degradation. Always use genuine Komatsu sensors or OEM-equivalent parts to ensure proper resistance curves.

Disclaimer: This guide provides general diagnostic procedures. Always consult the official Komatsu PC110-7 service manual and consider professional diagnostic support for complex electrical issues or ECM programming.