KomatsuPC800SE-7 Fault Code E93D: Complete Diagnostic Guide

What is KomatsuPC800SE-7 Fault Code E93D?

Fault Code E93D on the Komatsu PC800SE-7 indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition.

This diagnostic trouble code is triggered when the Engine Control Module (ECM) receives voltage readings outside the normal operating parameters from the coolant temperature sensor—typically above 4.9 volts. The sensor, located on the engine block near the thermostat housing, provides critical temperature data that influences fuel injection timing, cooling fan activation, and cold-start enrichment strategies.

On the SAA6D140E-5 engine powering this 80-ton class excavator, accurate coolant temperature monitoring is essential for preventing thermal damage and maintaining optimal combustion efficiency. Ignoring this code can lead to engine derate, overheating, or catastrophic failure.

Common Symptoms

• Check Engine warning lamp illuminated on the monitor panel
• Engine operating in derate mode with reduced power output
• Cooling fans running continuously at maximum speed (default failsafe)
• Inaccurate or erratic temperature gauge readings
• Difficulty achieving proper operating temperature during cold starts

Potential Causes

• Coolant temperature sensor failure (internal open circuit)
• Damaged or corroded wiring harness between sensor and ECM
• Poor ground connection at the sensor or ECM
• Connector corrosion from coolant leaks or environmental exposure
• Harness chafing against engine components (common wear point on high-hour machines)
• ECM internal fault (rare but possible on older units)

How to Troubleshoot and Fix Code E93D

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor connector located on the engine block. On used excavators, check for corrosion, coolant contamination, or bent pins. Examine the harness routing for abrasion points, particularly where wiring passes near the exhaust manifold.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the terminals. At 20°C (68°F), expect approximately 2.5-3.0 kΩ. An open-loop reading (OL) confirms sensor failure. Next, verify 5-volt reference and ground integrity at the harness connector with the key on.

Step 3: Harness Continuity Check Using Komatsu VHMS or compatible diagnostic software, perform a wiggle test while monitoring live data. Check continuity from the sensor connector to ECM pins. Repair any damaged wiring using weatherproof connectors and marine-grade heat shrink.

Step 4: Component Replacement If testing confirms sensor failure, replace with an OEM-specification unit. Clear the fault code using diagnostic software and verify proper temperature readings during 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.