What is Sumitomo SH240-6 Fault Code 117?

Fault Code 117 on the Sumitomo SH240-6 excavator indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects either an open circuit, short circuit, or out-of-range voltage signal from the coolant temperature sensor (also known as the water temperature sensor).

This sensor is critical for proper engine management on the SH240-6's diesel powerplant. The ECM relies on accurate coolant temperature data to adjust fuel injection timing, control engine warm-up cycles, activate cooling fans, and prevent overheating damage. When Code 117 appears, the ECM may default to a preset temperature value, potentially causing poor fuel economy, rough idling, or activation of engine protection modes that limit machine performance.

Common Symptoms

When Fault Code 117 is active on your Sumitomo SH240-6, operators typically experience:

• Warning light illumination on the instrument cluster, specifically the engine malfunction or check engine indicator
• Hard starting or extended cranking time, especially during cold weather conditions
• Rough idle or unstable engine RPM during warm-up periods
• Reduced hydraulic performance due to engine derate or power limitation modes
• Cooling fan running continuously at high speed, even when engine temperature appears normal

Potential Causes

The most common technical causes for Code 117 on used SH240-6 excavators include:

• Faulty coolant temperature sensor due to internal element degradation (common after 5,000+ operating hours)
• Corroded or loose electrical connectors at the sensor harness junction near the thermostat housing
• Damaged wiring harness caused by rubbing against engine components or heat exposure from exhaust manifold proximity
• Coolant contamination on sensor tip causing inaccurate readings (glycol breakdown or oil intrusion)
• ECM internal fault or corrupted sensor calibration data (less common but possible in high-hour machines)
• Poor ground connection at engine block grounding points affecting sensor circuit integrity

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Begin by locating the coolant temperature sensor on the engine block near the thermostat housing. Inspect the electrical connector for corrosion, bent pins, moisture intrusion, or loose connection. On used excavators, check the wiring harness routing for signs of chafing, heat damage, or previous repairs with electrical tape.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure sensor resistance. At room temperature (68°F/20°C), resistance should typically read 2,000-3,000 ohms (consult service manual for exact specifications). Check for voltage supply from the ECM: key on, engine off should show approximately 5 volts at the harness connector. Test for continuity between sensor ground and chassis ground.

Step 3: Sensor and Harness Evaluation If resistance readings are out of specification or show infinite/zero values, replace the coolant temperature sensor with a genuine Sumitomo or OEM-equivalent part. Before installation, clean the sensor bore thoroughly and apply appropriate thread sealant. If sensor tests correctly, trace the harness back to the ECM, checking for wire breaks or shorts to ground. Clear the fault code using diagnostic software and perform a test cycle.

Step 4: Advanced Diagnostics For persistent Code 117 after sensor replacement, use Sumitomo diagnostic software or compatible scan tool to monitor live coolant temperature data. Compare actual coolant temperature (verified with infrared thermometer) against ECM readings. Significant variance indicates potential ECM calibration issues requiring dealer-level programming.

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Disclaimer: This guide provides general troubleshooting information for Sumitomo SH240-6 Fault Code 117. Always consult the manufacturer's official service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional damage or safety hazards.