Komatsu PC400-8 Fault Code E15CA352: Complete Diagnostic Guide

What is Komatsu PC400-8 Fault Code E15CA352?

Fault code E15CA352 on the Komatsu PC400-8 indicates a malfunction in the engine coolant temperature (ECT) sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition.

This diagnostic trouble code is generated by the Engine Control Module (ECM) when the coolant temperature sensor signal falls outside the manufacturer's specified parameters. The ECT sensor, typically located near the thermostat housing, provides critical temperature data that the ECM uses to regulate fuel injection timing, cooling fan operation, and overall engine protection strategies.

On the SAA6D125E-5 engine powering the PC400-8, accurate coolant temperature readings are essential for proper cold-start enrichment and preventing thermal damage during heavy-duty operations.

Common Symptoms

• Check Engine warning lamp illuminated on the monitor panel
• Engine may enter derate mode, limiting power output and hydraulic performance
• Cooling fan running continuously at maximum speed regardless of actual temperature
• Inaccurate or erratic temperature gauge readings on the display
• Poor fuel economy and rough idle, particularly during cold starts

Potential Causes

The most frequent causes of E15CA352 on used PC400-8 excavators include:

• ECT sensor failure due to age, thermal cycling, or coolant contamination
• Wiring harness damage from vibration, particularly where the harness routes near the engine block
• Corroded connector pins at the sensor or ECM interface—common in machines operating in humid or coastal environments
• Open circuit caused by broken wires or loose terminal connections
• ECM internal fault (rare but possible on high-hour machines)

How to Troubleshoot and Fix Code E15CA352

Step 1: Visual Inspection Begin by inspecting the ECT sensor connector and associated wiring harness. On used excavators, check for chafed insulation, corrosion, or moisture intrusion. Pay particular attention to harness routing near hot exhaust components and areas prone to vibration wear.

Step 2: Electrical Testing Using a digital multimeter, measure the sensor's resistance. At 20°C (68°F), expect approximately 2,000-3,000 ohms. Verify the 5V reference voltage at the connector with the key on. An open circuit reading confirms sensor or wiring failure.

Step 3: Connector and Harness Repair Clean corroded terminals with electrical contact cleaner. For used machinery, replace damaged connectors entirely rather than attempting temporary repairs. Verify continuity between the sensor connector and ECM pins using Komatsu KOMTRAX Plus or equivalent diagnostic software.

Step 4: Component Replacement If testing confirms sensor failure, replace the ECT sensor with an OEM-specification part. Clear the fault code using diagnostic equipment and verify proper operation through a complete warm-up cycle.

---

Disclaimer: This guide is for informational purposes only. Always consult qualified heavy diesel technicians and refer to official Komatsu service documentation before performing repairs on your equipment.