What is Kobelco SK130-8 Fault Code 6371?

Fault Code 6371 on the Kobelco SK130-8 excavator indicates a malfunction in the engine control system, specifically related to the intake air temperature sensor circuit or an abnormal reading from the intake air temperature (IAT) sensor. This code is triggered when the Engine Control Module (ECM) detects a voltage signal outside the normal operating range from the IAT sensor, which monitors the temperature of air entering the engine's combustion chambers.

The intake air temperature sensor plays a critical role in optimizing fuel injection timing and air-fuel ratio calculations. On the Kobelco SK130-8's Hino J05E engine, accurate IAT readings ensure proper combustion efficiency, emissions control, and overall engine performance. When this sensor fails or provides erratic data, the ECM cannot properly adjust fuel delivery, potentially leading to reduced power output and increased fuel consumption.

Common Symptoms

When Code 6371 is active on your SK130-8, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Reduced engine power or noticeable loss of performance, especially during cold starts
• Black or gray exhaust smoke indicating improper fuel mixture
• Rough idling or inconsistent engine RPM at startup
• Increased fuel consumption due to ECM defaulting to pre-programmed substitute values

Potential Causes

Several factors commonly trigger Code 6371 on used Kobelco excavators:

• Faulty IAT sensor due to age-related degradation or contamination from oil vapors and debris in the intake system
• Damaged or corroded wiring harness connecting the sensor to the ECM—particularly common at connector points exposed to engine heat and vibration
• Shorted or open circuits in the sensor wiring, often caused by harness chafing against engine components (known issue near the intake manifold on SK130-8 models)
• Corroded electrical connectors from moisture infiltration, especially on machines operating in humid or marine environments
• ECM internal fault (rare, but possible in high-hour used machines)

How to Troubleshoot and Fix Code 6371

Step 1: Visual Inspection Begin by inspecting the IAT sensor located on the intake manifold. Check for physical damage, oil contamination, or loose connections. On used excavators, carefully examine the entire wiring harness from sensor to ECM for signs of abrasion, melting, or rodent damage—pay special attention to areas where the harness contacts metal brackets or hot engine surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the IAT sensor connector and measure resistance across the sensor terminals. Compare readings against Kobelco specifications (typically 2,000-3,000 ohms at 68°F/20°C). Check voltage supply at the harness connector with ignition ON—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Circuit Continuity Check Test for continuity and short circuits in the wiring between the sensor connector and ECM pins. Look specifically for shorted-to-ground conditions that commonly occur where harnesses rub through insulation. On used SK130-8 excavators, inspect connector pins for corrosion or "green oxidation" that increases resistance.

Step 4: Component Replacement If the sensor tests outside specifications or wiring shows damage, replace the faulty component using genuine Kobelco or OEM-equivalent parts. After replacement, clear codes using Kobelco diagnostic software or a compatible scanner and perform a test run under load.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Kobelco service manual for your specific serial number and seek professional diagnostic assistance for complex electrical issues. Improper repairs may cause further damage to ECM components.