Sumitomo SH240-5 Fault Code 113: Complete Diagnostic Guide

What is Sumitomo SH240-5 Fault Code 113?

Fault Code 113 on the Sumitomo SH240-5 excavator indicates an Engine Coolant Temperature (ECT) Sensor Circuit malfunction or abnormal voltage reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects a signal from the coolant temperature sensor that falls outside the acceptable voltage range, typically indicating an open circuit, short circuit, or sensor degradation.

The ECT sensor is critical for the SH240-5's engine management system because it directly influences fuel injection timing, idle speed control, and engine protection protocols. When this sensor fails or sends incorrect data, the ECM cannot properly regulate engine temperature, potentially leading to overheating, poor fuel economy, or engine derate modes that limit machine performance.

Common Symptoms

When Code 113 is active on your Sumitomo SH240-5, operators typically experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Erratic temperature gauge readings or gauge stuck at cold/hot positions regardless of actual engine temperature
• Hard starting conditions, especially in cold weather, due to improper fuel enrichment
• Cooling fan running continuously at high speed, even when engine is cold
• Engine performance issues including rough idle, hesitation, or reduced power output
• Potential engine derate mode activation if ECM enters failsafe operation

Potential Causes

For used Sumitomo SH240-5 excavators, Code 113 typically stems from these common issues:

• Failed or degraded ECT sensor due to age, thermal stress, or internal resistance drift
• Damaged wiring harness between sensor and ECM, particularly at flex points near the engine block
• Corroded or loose electrical connectors at the sensor or ECM terminals—common in machines exposed to harsh environments
• Coolant contamination on sensor terminals causing false readings or short circuits
• ECM internal fault (less common) affecting temperature input processing
• Aftermarket sensor incompatibility if previous repairs used non-OEM parts

How to Troubleshoot and Fix Code 113

Step 1: Visual Inspection Begin with a thorough inspection of the ECT sensor located on the engine block (typically near the thermostat housing). Check for physical damage, coolant leaks around the sensor base, and connector corrosion. On used excavators, pay special attention to harness chafing against engine components or frame rails—a common failure point on the SH240-5.

Step 2: Electrical Testing Using a digital multimeter, disconnect the ECT sensor connector and measure resistance across sensor terminals. At room temperature (68°F/20°C), resistance should typically read 2,000-3,000 ohms (consult service manual for exact specifications). Also check for continuity in the wiring harness from sensor to ECM and verify ground circuit integrity.

Step 3: Voltage Signal Verification With the sensor connected and ignition ON (engine OFF), backprobe the sensor connector and measure voltage. You should see approximately 5 volts reference voltage from the ECM. If voltage is absent or incorrect, suspect ECM issues or harness faults rather than the sensor itself.

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine OEM Sumitomo ECT sensor. For used machines, always apply dielectric grease to connector terminals to prevent future corrosion. After replacement, clear codes using diagnostic software and perform a test cycle to verify repair.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues or if you lack proper diagnostic tools.