What is Kobelco SK140LC-8 Fault Code C013?

Kobelco SK140LC-8 Fault Code C013 indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormal voltage signal being sent to the Engine Control Module (ECM). This code typically registers when the ECM receives a voltage reading outside the expected range (either too high or too low) from the coolant temperature sensor, which monitors engine operating temperature.

For the Kobelco SK140LC-8's Isuzu engine, accurate coolant temperature data is critical for proper fuel injection timing, idle speed control, and engine protection systems. When this sensor circuit fails, the ECM cannot properly manage engine temperature, potentially leading to overheating, poor fuel economy, or engine protection shutdowns that halt jobsite productivity.

Common Symptoms

• Check Engine Light illuminated on the instrument panel, often accompanied by a specific warning icon
• Hard starting conditions, particularly when the engine is cold, due to incorrect fuel enrichment calculations
• Erratic engine idle or rough running, especially noticeable during warm-up periods
• Engine derate mode activation, limiting power output to prevent potential overheating damage
• Cooling fan running continuously at high speed, even when engine temperature appears normal

Potential Causes

The most common technical causes for Code C013 on used SK140LC-8 excavators include:

• Coolant temperature sensor failure due to internal resistance breakdown after years of heat cycling
• Corroded or loose electrical connectors at the sensor or ECM harness connection points—extremely common on machines operating in wet or corrosive environments
• Damaged wiring harness, particularly where the sensor wire runs near the engine block or exhaust components (known rub point on this model)
• Failed ECM input circuit or internal ECM damage from previous electrical surges
• Contaminated coolant causing sensor element coating or corrosion
• Poor ground connection affecting sensor signal return path

How to Troubleshoot and Fix Code C013

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor (located on the engine's thermostat housing) and its connector for obvious damage, corrosion, or coolant leaks. On used excavators, check for harness wear where the wire passes through the engine valley—this is a documented failure point on SK140LC-8 models.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms (consult Kobelco service manual for exact specifications). Test the harness voltage with key on/engine off—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Connector and Ground Verification Clean all connector terminals with electrical contact cleaner and apply dielectric grease. Verify ground circuit continuity between the sensor ground pin and chassis ground (should read less than 1 ohm). For used machines, this step often resolves intermittent codes without parts replacement.

Step 4: Component Replacement If sensor resistance is out of specification or harness shows open/short circuit conditions, replace the faulty component. Always use OEM or equivalent quality parts and ensure proper torque specifications when installing the sensor to prevent coolant leaks.

Step 5: Clear Code and Verify Using Kobelco diagnostic software or a compatible scan tool, clear the fault code and monitor for recurrence during a complete heat cycle.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Kobelco service manual for your specific machine serial number and consider professional diagnostic services for complex electrical issues or if you lack proper diagnostic equipment.