What is Sumitomo SH240-5 Fault Code 117?

Fault Code 117 on the Sumitomo SH240-5 excavator indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM). This diagnostic trouble code (DTC) is triggered when the ECM receives voltage signals outside the expected range from the coolant temperature sensor, or when the sensor fails to communicate proper temperature data during engine operation.

The coolant temperature sensor plays a critical role in the SH240-5's performance management system. It provides real-time data that allows the ECM to adjust fuel injection timing, idle speed, and engine protection protocols. When Code 117 activates, the engine may enter a protective derate mode to prevent potential overheating damage, significantly impacting productivity on job sites.

Common Symptoms

When Fault Code 117 is active on your Sumitomo SH240-5, operators typically experience:

• Check engine warning light illuminated on the instrument cluster
• Engine running in limp mode with reduced power output and limited RPM
• Difficulty starting the engine, particularly during cold starts
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions
• Excessive white smoke during warm-up due to improper fuel mixture adjustments
• Engine cooling fans running continuously at maximum speed

Potential Causes

The most common technical reasons for Code 117 on used SH240-5 excavators include:

• Faulty coolant temperature sensor due to internal resistance drift or element failure (common after 5,000+ operating hours)
• Damaged or corroded wiring harness connections at the sensor plug, especially where the harness routes near the engine block
• Shorted or open circuits in the sensor wiring caused by insulation breakdown from heat exposure
• Corroded ECM connector pins affecting signal transmission
• Low coolant level causing intermittent sensor exposure to air instead of coolant
• Failed ECM (rare, but possible in high-hour used machines with electrical system history)

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for physical damage, coolant leaks around the sensor base, and verify adequate coolant level. On used excavators, carefully examine the wiring harness for signs of rubbing against the engine block, melted insulation, or brittle wires from prolonged heat exposure.

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 between 2,000-3,000 ohms; consult your service manual for exact specifications. Test the harness continuity from the sensor connector back to the ECM, checking for opens or shorts to ground. Inspect connector pins for corrosion or bent terminals—a frequent issue in machines operating in wet or marine environments.

Step 3: Diagnostic Software Verification If available, connect Sumitomo diagnostic software or a compatible scan tool to monitor live coolant temperature data. Compare the sensor reading against actual engine temperature using an infrared thermometer. A discrepancy of more than 15-20°F indicates sensor failure. Clear the code after repairs and perform a test cycle to verify the fix holds under operating temperature.

Step 4: Component Replacement Replace the coolant temperature sensor with an OEM or high-quality aftermarket unit, applying thread sealant as specified. For used excavators with over 8,000 hours, consider replacing the sensor pigtail connector simultaneously, as heat cycling degrades connector integrity over time.

---

Disclaimer: This guide provides general troubleshooting information for Fault Code 117. Always consult the official Sumitomo service manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.