Sumitomo SH220LC-6 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH220LC-6 Fault Code 1113?

Fault Code 1113 on the Sumitomo SH220LC-6 indicates a malfunction in the Engine Coolant Temperature (ECT) sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition. This code is generated when the Engine Control Module (ECM) receives a voltage reading outside the normal operating range (typically above 4.5 volts), suggesting the sensor or its wiring has failed.

The ECT sensor plays a critical role in engine management by monitoring coolant temperature and sending data to the ECM for fuel injection timing, idle speed control, and overheat protection. On used excavators like the SH220LC-6, this sensor's accuracy directly affects engine performance, fuel efficiency, and prevents catastrophic overheating damage to the powerplant.

Common Symptoms

When Code 1113 is active, operators typically experience:

• Check Engine light illuminated on the instrument panel with possible overheat warning
• Hard starting conditions, especially during cold weather, due to incorrect fuel enrichment
• Rough idle or erratic engine RPM fluctuations at low speeds
• Reduced engine power or derate mode activation as a protective measure
• Cooling fan running continuously at maximum speed regardless of actual engine temperature

Potential Causes

The most common technical failures triggering this fault code include:

• Open circuit in ECT sensor wiring harness, particularly at flex points near the engine mount where vibration causes wire fatigue
• Failed ECT sensor with internal resistance breakdown (common on machines with 5,000+ operating hours)
• Corroded or loose connector pins at the sensor plug, especially on excavators exposed to moisture or coolant leaks
• Damaged ECM ground connections creating voltage reference issues
• Coolant contamination causing sensor element degradation in used machines with poor maintenance history
• Harness chafing against engine components—a known issue on SH220LC-6 models near the thermostat housing

How to Troubleshoot and Fix Code 1113

Step 1: Visual Inspection Begin by inspecting the ECT sensor located on the engine block near the thermostat housing. Check for coolant leaks, corrosion on the connector, and examine the wiring harness for visible damage, particularly where it routes along the engine valley. On used excavators, look for evidence of previous repairs or electrical tape indicating past issues.

Step 2: Electrical Testing Disconnect the ECT sensor connector and use a digital multimeter to measure resistance across the sensor terminals. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms (consult your service manual for exact specifications). If the reading shows infinite resistance (open circuit) or zero ohms (short circuit), replace the sensor.

Step 3: Circuit Verification With the sensor disconnected, measure voltage at the ECM harness connector side. You should see approximately 5 volts reference voltage from the ECM. Check continuity between the sensor ground wire and chassis ground—resistance should be less than 1 ohm. Inspect connector pins for corrosion and apply dielectric grease during reassembly.

Step 4: Harness and ECM Check If sensor and basic circuit tests pass, trace the wiring harness completely from sensor to ECM, checking for rubbing points, especially near engine mounts and frame rails common on older SH220LC-6 models. Test ECM ground straps for integrity. If all wiring proves sound, ECM malfunction may be present—consult factory diagnostic software for deeper analysis.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the Sumitomo SH220LC-6 service manual for exact specifications. If you're uncomfortable performing electrical diagnostics on used excavators, seek assistance from a certified heavy equipment technician to avoid misdiagnosis or further damage.