What is Kobelco SK350-6E Fault Code A-2?

Kobelco SK350-6E Fault Code A-2 indicates a malfunction in the engine control system, specifically related to abnormal communication between the Engine Control Module (ECM) and the main controller or a sensor circuit failure within the engine management system. This diagnostic trouble code (DTC) is part of Kobelco's proprietary monitoring system that continuously evaluates engine performance parameters and electrical circuit integrity.

On the SK350-6E model, this code typically signals that the ECM has detected an interruption in data transmission or abnormal voltage readings from critical engine sensors. This is particularly important because the SK350-6E's Hino J05E engine relies heavily on precise electronic control for fuel injection timing, turbocharger management, and emissions compliance. When Code A-2 is active, the machine may enter a derate mode to prevent potential engine damage, significantly impacting productivity on job sites.

Common Symptoms

When Fault Code A-2 is active on your Kobelco SK350-6E, you may experience:

• Engine warning lamp illuminated on the instrument cluster with reduced power output
• Limited engine RPM or inability to reach full operating speed (typically capped at 1500-1800 RPM)
• Intermittent stalling or rough idling, especially during cold starts
• Erratic hydraulic response due to inconsistent engine speed regulation
• Complete shutdown in severe cases, requiring a system reset to restart

Potential Causes

The most common technical causes for Code A-2 on used SK350-6E excavators include:

• ECM connector corrosion – The main ECM harness connector (located near the battery box) is prone to moisture infiltration on machines with 5,000+ operating hours
• Damaged CAN bus wiring – Communication wires between the ECM and main controller can chafe against the engine block mounting bracket
• Failing crank position sensor or cam position sensor – Common wear items that degrade signal quality
• Low battery voltage (below 22V on this 24V system) causing ECM communication dropout
• ECM internal failure – Less common but possible in high-hour machines exposed to extreme heat or vibration

How to Troubleshoot and Fix Code A-2

Step 1: Preliminary Inspection Begin with a thorough visual inspection of the engine wiring harness, focusing on areas where cables contact metal surfaces. On used excavators, check specifically behind the fuel filter housing and along the valve cover edge where harness chafing is common. Look for abraded insulation, corroded pins, or loose connections.

Step 2: Voltage and Resistance Testing Using a digital multimeter, verify battery voltage under load (should maintain above 23V during cranking). Test the ECM power supply circuits at the main connector—you should see consistent 24V on power pins and solid ground continuity (less than 0.5 ohms resistance). Check sensor resistance values: crank position sensor should read 190-250 ohms, cam sensor 200-280 ohms at room temperature.

Step 3: Communication Circuit Diagnosis Connect Kobelco diagnostic software (MAPS or compatible interface) to read live data streams. Monitor CAN bus voltage between the ECM and main controller—proper communication requires 2.5V average with fluctuation between 1.5-3.5V. If communication is absent, inspect termination resistors and measure continuity on CAN-High and CAN-Low wires (typically green and yellow wires in the main harness).

Step 4: Component Replacement Protocol After identifying the failed component, always clean connector terminals with electrical contact cleaner and apply dielectric grease before reassembly. For used machinery, replace sensor pigtails simultaneously with sensors to prevent recurrence. Clear codes, perform a stationary regeneration cycle, and conduct a 20-minute operational test under load.

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Disclaimer: This guide provides general troubleshooting information for Kobelco SK350-6E excavators. Always consult the official Kobelco service manual and consider professional diagnostic services for complex electrical issues. Improper repairs may void warranties or cause additional damage.