What is Kobelco SK350LC-8 Fault Code I113?

Fault Code I113 on the Kobelco SK350LC-8 excavator indicates an abnormal signal from the engine coolant temperature sensor or circuit malfunction. This code is triggered when the Engine Control Module (ECM) detects an out-of-range voltage reading from the coolant temperature sensor, typically due to an open circuit, short circuit, or sensor failure.

The coolant temperature sensor plays a critical role in engine management on this excavator model. It provides real-time data to the ECM, which adjusts fuel injection timing, idle speed, and activates engine protection protocols. On used SK350LC-8 machines, this sensor's accuracy is essential for preventing overheating and maintaining optimal combustion efficiency. Ignoring this fault can lead to poor fuel economy, increased emissions, and potential engine damage from inadequate thermal management.

Common Symptoms

When Code I113 is active, operators typically experience:

• Engine warning light illuminated on the instrument cluster or diagnostic panel
• Hard starting or extended cranking time, especially in cold conditions
• Rough idle or irregular engine RPM fluctuations during warm-up
• Engine derate mode activating prematurely, limiting machine performance and hydraulic power
• Cooling fan running continuously at high speed regardless of actual engine temperature

Potential Causes

The most common technical reasons for I113 appearing on used SK350LC-8 excavators include:

• Coolant temperature sensor failure due to age-related internal resistance drift or element corrosion
• Wiring harness damage at known rub points near the engine block or behind the radiator shroud
• Corroded or loose connector terminals at the sensor plug, especially on machines operating in harsh or marine environments
• ECM ground circuit issues causing voltage reference problems across multiple sensors
• Damaged sensor mounting threads allowing coolant leakage and sensor exposure to contaminants
• Aftermarket sensor incompatibility from previous non-OEM replacements on used machines

How to Troubleshoot and Fix Code I113

Step 1: Visual Inspection Begin with a thorough inspection of the coolant temperature sensor located on the engine block (typically near the thermostat housing). Check for coolant leaks, physical damage, and corrosion on the connector terminals. On used excavators, pay special attention to harness wear where wiring contacts engine components or frame edges.

Step 2: Electrical Testing Using a digital multimeter, check sensor resistance. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms (consult the SK350LC-8 service manual for exact specifications). Test circuit continuity from the sensor connector back to the ECM. Check for shorts to ground by measuring resistance between each sensor wire and chassis ground—readings should be infinite (open circuit).

Step 3: Live Voltage Testing With the ignition on but engine off, measure reference voltage at the sensor connector. You should see approximately 5 volts on the signal wire. Start the engine and monitor voltage changes as the engine warms—voltage should decrease steadily as temperature rises. Erratic readings indicate sensor failure.

Step 4: Address Root Cause For used machines, replace the coolant temperature sensor with OEM Kobelco parts to ensure proper resistance curves. If wiring damage is found, repair or replace the affected harness section and secure it away from heat sources and moving parts. Clean all connector terminals with electrical contact cleaner and apply dielectric grease. Clear the fault code using Kobelco diagnostic software or a compatible scan tool and verify the repair through a complete heat cycle.

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Disclaimer: This guide provides general troubleshooting information. Always consult the Kobelco SK350LC-8 service manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with heavy equipment repair procedures.