Komatsu PC750LC-7 Fault Code E216: Complete Diagnostic Guide

What is Komatsu PC750LC-7 Fault Code E216?

Fault Code E216 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM). This code specifically relates to the coolant temperature sensor sending irregular voltage signals or detecting temperatures outside the normal operating parameters for the SAA6D140E-3 engine.

This fault is critical for the PC750LC-7 because the ECM relies on accurate coolant temperature data to manage fuel injection timing, engine protection protocols, and hydraulic system performance. When E216 triggers, the engine may enter a protective derate mode to prevent overheating damage, significantly impacting productivity on job sites.

Common Symptoms

When Code E216 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Reduced engine power or automatic derate limiting RPM and hydraulic flow
• Erratic temperature gauge readings showing unusually high or low coolant temperatures
• Hard starting conditions or rough idle, especially during cold starts
• Increased fuel consumption due to ECM operating in default "limp mode" parameters

Potential Causes

The most common technical causes for E216 on used PC750LC-7 excavators include:

• Faulty coolant temperature sensor (common failure point after 8,000+ operating hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at connector pins
• Shorted or open circuit in the sensor signal wire due to harness rubbing against engine components
• Corroded connector terminals at the sensor or ECM connection points (especially in high-moisture environments)
• Low coolant level causing intermittent sensor exposure and false readings
• Failed ECM (rare, but possible in machines with electrical system history)

How to Troubleshoot and Fix Code E216

Step 1: Visual Inspection Begin by checking coolant level in the radiator and overflow tank. Inspect the coolant temperature sensor (located on the engine block near the thermostat housing) for physical damage, coolant leaks, or corrosion. On used excavators, carefully examine the wiring harness for wear points where it contacts the engine or frame.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms (consult your service manual for exact specifications). Check for continuity in the signal wire from sensor to ECM, and verify ground integrity.

Step 3: Connector and Voltage Checks Inspect connector pins for corrosion, bent terminals, or moisture intrusion—common issues in older machines. With ignition on and sensor disconnected, measure reference voltage at the harness connector (should read approximately 5 volts). If voltage is absent, trace the circuit toward the ECM.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu coolant temperature sensor (Part #6732-81-3210 or equivalent). For used excavators, always apply dielectric grease to connector terminals during reassembly to prevent future corrosion. Clear codes using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then monitor during operation.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC750LC-7 service manual and consider professional assistance from certified Komatsu technicians for complex electrical diagnostics or if safety concerns arise.