Komatsu PC750-7 Fault Code E201: Complete Diagnostic Guide

What is Komatsu PC750-7 Fault Code E201?

Fault Code E201 on the Komatsu PC750-7 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.

The coolant temperature sensor plays a critical role in the PC750-7's SAA6D140E-5 engine management system. It provides real-time data to the ECM for fuel injection timing, engine protection protocols, and hydraulic system temperature compensation. When this sensor fails or sends erratic signals, the excavator's performance and longevity are directly compromised, potentially leading to overheating or inefficient combustion.

Common Symptoms

When Code E201 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Reduced engine power or derate mode activation to prevent thermal damage
• Inaccurate coolant temperature readings displayed on the instrument cluster (showing extremely high or low values)
• Difficult cold starts or rough idling, especially in colder climates
• Increased fuel consumption due to improper fuel mapping based on faulty temperature data

Potential Causes

The most common technical causes for E201 on used PC750-7 excavators include:

• Faulty coolant temperature sensor due to age-related degradation or internal element failure
• Damaged wiring harness or corroded connectors, particularly at harness rub points near the engine block
• Poor electrical ground connection at the sensor mounting location
• Coolant contamination causing sensor element coating or corrosion
• ECM internal fault (rare, but possible in high-hour machines)
• Intermittent short circuits in the sensor wiring from vibration damage common in older equipment

How to Troubleshoot and Fix Code E201

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block (typically near the thermostat housing). Check for physical damage, coolant leaks, or corrosion on the connector pins. On used excavators, examine the wiring harness for wear points where it contacts the engine or frame—this is a common failure point on the PC750-7.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. At 20°C (68°F), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Check voltage supply from the ECM—you should see approximately 5 volts at the sensor connector with the key on, engine off.

Step 3: Circuit Verification Test for continuity between the sensor connector and the ECM pins. Check for shorts to ground or power. Inspect the ground connection at the sensor mounting point—clean and tighten if necessary. For used machines, corrosion in connectors is extremely common and often overlooked.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu sensor (Part #6732-81-3110 or equivalent). After replacement, clear codes using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then perform a test run to verify repair.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number. Complex electrical issues should be diagnosed by certified technicians with proper diagnostic equipment.