Komatsu PC70-8 Fault Code E-13: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code E-13?

Fault Code E-13 on the Komatsu PC70-8 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 system.

The hydraulic oil temperature sensor is critical for the PC70-8's performance management system. It monitors oil viscosity conditions and prevents overheating damage to hydraulic components. When this sensor fails or sends erratic signals, the ECM cannot properly regulate system performance, potentially leading to reduced efficiency or component damage. For used excavators, this code often appears due to sensor degradation or wiring issues common in machines with extended operating hours.

Common Symptoms

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

• Warning light illuminated on the instrument panel (typically a hydraulic system indicator)
• Inaccurate hydraulic oil temperature readings or gauge malfunction
• Reduced hydraulic system performance or derate mode activation in extreme cases
• Intermittent code appearance, especially during cold starts or after extended operation
• Potential activation of backup cooling fan cycles regardless of actual oil temperature

Potential Causes

The most common technical causes for E-13 on used PC70-8 excavators include:

• Hydraulic oil temperature sensor failure due to internal element degradation
• Damaged or corroded wiring harness connections at the sensor plug
• Chafed wires along the harness routing near the hydraulic tank (known wear point on this model)
• Corroded or loose ground connections affecting sensor circuit integrity
• ECM internal fault (rare, but possible in high-hour machines)
• Contaminated sensor tip from degraded hydraulic oil or debris accumulation

How to Troubleshoot and Fix Code E-13

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor on the hydraulic tank. Inspect the sensor connector for corrosion, oil contamination, or loose pins. Check the wiring harness from sensor to ECM for visible damage, especially where it routes near moving components or sharp edges.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. Compare readings against Komatsu specifications (typically 200-400 ohms at 20°C). Check voltage supply at the harness connector (should read approximately 5 volts with ignition on). Verify ground circuit continuity to the ECM.

Step 3: Component Replacement and Verification If readings are out of specification, replace the temperature sensor with a genuine Komatsu part. For used excavators, always clean connector terminals with electrical contact cleaner and apply dielectric grease before reconnection. Clear the fault code using Komatsu diagnostic software or by disconnecting the battery for 10 minutes, then test operate the machine.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual and consider professional technician assistance for complex electrical diagnostics.