Komatsu PC70-8 Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code E-17?

Fault Code E-17 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 plays a critical role in protecting the PC70-8's hydraulic system by monitoring operating temperatures. When oil temperatures exceed safe limits or the sensor circuit fails, the ECM logs this fault to prevent potential damage to hydraulic components, seals, and pumps. For this compact excavator model, maintaining proper hydraulic temperature monitoring is essential for optimal performance and longevity.

Common Symptoms

When Code E-17 is active, operators typically experience:

• Warning light illuminated on the instrument panel (typically a hydraulic system indicator)
• Erratic or incorrect hydraulic oil temperature readings on the display
• Hydraulic system derate or reduced performance in extreme cases
• Intermittent fault 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-17 on used PC70-8 excavators include:

• Faulty hydraulic oil temperature sensor due to age-related degradation or contamination
• 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
• Failed ECM input circuit (rare, but possible in high-hour machines)
• Contaminated hydraulic oil causing sensor element fouling

How to Troubleshoot and Fix Code E-17

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 damaged pins. Check the wiring harness 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 for voltage supply at the harness connector (should read approximately 5V reference voltage from the ECM).

Step 3: Circuit Verification Test harness continuity from sensor connector to the ECM. On used excavators, pay special attention to connector terminals for "green corrosion" and harness sections that may have experienced rubbing wear over thousands of operating hours.

Step 4: Component Replacement If sensor resistance is out of specification or harness damage is found, replace the faulty component using genuine Komatsu parts. Clear the fault code using Komatsu diagnostic software (KOMTRAX or compatible scan tool) and verify repair by monitoring live data during operation.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and seek professional assistance for complex electrical diagnostics or repairs.