Sumitomo SH300-6 Fault Code 217: Complete Diagnostic Guide

What is Sumitomo SH300-6 Fault Code 217?

Fault Code 217 on the Sumitomo SH300-6 excavator indicates a malfunction in the engine coolant temperature sensor circuit, specifically an abnormally high voltage reading or open circuit condition. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects voltage levels outside the acceptable range (typically above 4.8V) from the coolant temperature sensor (CTS).

The coolant temperature sensor plays a critical role in the SH300-6's engine management system, providing real-time data that affects fuel injection timing, idle speed control, and cooling fan operation. When this sensor circuit fails, the ECM defaults to a predetermined temperature value, which can lead to suboptimal engine performance, increased fuel consumption, and potential overheating issues on this hydraulic excavator model.

Common Symptoms

When Code 217 is active on your SH300-6, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Engine running rich or experiencing rough idle conditions, especially during cold starts
• Cooling fan running continuously at maximum speed regardless of actual engine temperature
• Reduced engine power or performance, particularly noticeable during heavy digging operations
• Difficulty starting in cold weather conditions due to incorrect fuel mixture calculations

Potential Causes

The most common technical reasons for Code 217 on used SH300-6 excavators include:

• Open circuit in the sensor wiring harness – particularly at flex points near the engine mount where vibration causes wire breakage
• Failed coolant temperature sensor with internal open circuit (common after 5,000+ operating hours)
• Corroded or loose connector terminals at the sensor plug, especially on machines operated in wet or corrosive environments
• Damaged ECM wiring due to rodent activity or improper previous repairs
• Faulty ECM (rare, but possible on high-hour machines with moisture intrusion)

How to Troubleshoot and Fix Code 217

Step 1: Visual Inspection Begin by locating the coolant temperature sensor on the engine block (typically near the thermostat housing). Inspect the sensor connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the wiring harness for rubbing points, cracked insulation, or previous repair attempts using electrical tape.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to check resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. If the reading shows infinite resistance (OL), the sensor has failed internally and requires replacement.

Step 3: Circuit Verification With the sensor disconnected, measure voltage at the ECM-side connector. You should see approximately 5V reference voltage from the ECM. If voltage is absent, trace the harness back to the ECM, checking for breaks or shorts to ground. Pay special attention to harness routing near the hydraulic pump and swing motor areas where chafing commonly occurs.

Step 4: Sensor Replacement and Verification If the sensor tests faulty, replace it with an OEM-equivalent part rated for the Sumitomo SH300-6. After installation, clear the fault code using diagnostic software compatible with Sumitomo excavators and perform a test cycle to confirm proper operation.

---

Disclaimer: This guide provides general diagnostic information for Code 217. Always consult the official Sumitomo service manual for your specific machine's serial number range, and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with excavator electrical systems.