Komatsu PC70-8 Fault Code E-16: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code E-16?

Fault Code E-16 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-16 is active, operators typically experience:

• Warning light illuminated on the instrument panel (typically a hydraulic system indicator)
• Reduced hydraulic system performance or sluggish operation, especially during warm-up
• Derate mode activation, limiting engine RPM to protect the hydraulic system
• Inaccurate hydraulic oil temperature readings on the display (showing abnormally high or low values)
• Intermittent code activation that may clear and return during operation

Potential Causes

The most common technical causes for E-16 on used PC70-8 excavators include:

• Hydraulic oil temperature sensor failure due to age, heat cycling, or internal component breakdown
• Damaged or corroded wiring harness connections at the sensor plug (common wear point near the hydraulic tank)
• Chafed wires along the harness routing path, particularly where the harness contacts the frame or hydraulic lines
• Corroded or loose ground connections affecting sensor circuit integrity
• ECM internal fault (rare, but possible in high-hour machines)
• Contaminated hydraulic oil causing sensor element fouling

How to Troubleshoot and Fix Code E-16

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor (typically mounted on or near the hydraulic tank). Inspect the sensor connector for corrosion, oil contamination, or damaged pins. On used excavators, check the entire wiring harness for rub points, 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 the sensor terminals. Compare readings against Komatsu specifications (typically 200-400 ohms at room temperature, varying with temperature). Check for voltage supply at the harness connector (should read approximately 5 volts with key on, engine off).

Step 3: Circuit Verification Test harness continuity from the sensor connector back to the ECM. Check for shorts to ground or open circuits. Inspect ground connections and clean/tighten as needed.

Step 4: Component Replacement If sensor readings are out of specification or the harness shows damage, replace the faulty component. For used machines, consider replacing both the sensor and connector if corrosion is present. Clear codes using Komatsu diagnostic software and perform a test cycle.

---

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual and consider professional technician assistance for complex repairs, especially on used equipment with unknown service history.