Sumitomo SH240-6 Fault Code 113: Complete Diagnostic Guide

What is Sumitomo SH240-6 Fault Code 113?

Fault Code 113 on the Sumitomo SH240-6 excavator indicates an Engine Coolant Temperature (ECT) Sensor Circuit High Voltage condition. This diagnostic trouble code triggers when the Engine Control Module (ECM) detects an abnormally high voltage signal from the coolant temperature sensor circuit, typically above 4.5 volts.

The ECT sensor is critical for the SH240-6's engine management system, as it directly influences fuel injection timing, idle speed control, and engine protection protocols. When this sensor circuit malfunctions, the ECM cannot accurately monitor engine operating temperature, potentially leading to improper fuel delivery, overheating risks, or unnecessary engine derating to prevent damage.

Common Symptoms

When Code 113 is active on your SH240-6, you may experience:

• Check Engine Light or malfunction indicator illuminated on the instrument panel
• Hard starting conditions, especially when the engine is cold
• Rough idle or irregular engine RPM during warm-up phase
• Poor fuel economy due to ECM defaulting to cold-start fuel maps
• Engine derating or reduced power output as a protective measure
• Cooling fan running continuously at high speed regardless of actual engine temperature

Potential Causes

The most common technical causes for Code 113 on used SH240-6 excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing near the engine block mounting points
• Failed ECT sensor with internal resistance breakdown (common after 5,000+ operating hours)
• Corroded or damaged connector pins at the sensor or ECM connection points
• Shorted sensor ground wire creating false high-voltage readings
• ECM internal fault (rare, but possible in high-hour machines)
• Aftermarket sensor incompatibility if previous repairs used non-OEM parts

How to Troubleshoot and Fix Code 113

Step 1: Visual Inspection Begin by inspecting the ECT sensor located on the engine block (typically near the thermostat housing). Check for physical damage, coolant leaks, or corrosion on the two-wire connector. On used excavators, examine the wiring harness for wear points where it contacts the engine or frame.

Step 2: Electrical Testing With ignition off, disconnect the ECT sensor connector. Using a digital multimeter, measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. If readings show infinite resistance (open circuit) or zero ohms (short circuit), replace the sensor.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition on, measure voltage at the ECM-side harness connector. You should see approximately 5 volts reference voltage on the signal wire. If voltage exceeds 5 volts or shows battery voltage (12-24V), inspect for wiring shorts to positive or harness damage.

Step 4: Harness Continuity Test Check continuity between the sensor connector and ECM pins (consult service manual for specific pin identification). Also verify proper ground circuit continuity. Resistance should be less than 1 ohm for both signal and ground wires.

Step 5: Connector Restoration For used machines, corrosion is frequently the culprit. Clean all connector pins with electrical contact cleaner and apply dielectric grease to prevent moisture intrusion. Ensure connector lock mechanisms engage properly.

Step 6: Clear Code and Test After repairs, clear the fault code using Sumitomo diagnostic software or compatible scan tool. Run the engine through a complete warm-up cycle while monitoring live ECT sensor data to verify readings climb smoothly from ambient to operating temperature (typically 180-200°F/82-93°C).

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Disclaimer: This guide provides general diagnostic information for Sumitomo SH240-6 excavators. Always consult the manufacturer's official service manual for model-specific procedures and specifications. If you're uncomfortable performing electrical diagnostics, contact a certified Sumitomo technician or qualified heavy equipment mechanic to prevent further damage to your machine's electrical system.