What is Kobelco SK330-6E Fault Code A-2?

Kobelco SK330-6E Fault Code A-2 indicates a malfunction in the engine pre-heating system, specifically related to the glow plug relay circuit or intake air heater failure. This code is stored in the engine's Electronic Control Module (ECM) when it detects abnormal voltage, resistance, or circuit continuity issues within the pre-heating system that prepares the combustion chambers for cold starts.

The pre-heating system is critical for diesel engines, particularly in the Kobelco SK330-6E's Hino J05E or similar diesel powerplant. Without proper glow plug function, cold-start performance deteriorates significantly, leading to hard starting, excessive white smoke during startup, and increased engine wear. In used excavators, this system often degrades due to corrosion, worn relays, or damaged wiring harnesses exposed to years of environmental stress.

Common Symptoms

When Code A-2 is active on your SK330-6E, you may experience:

• Difficult or failed cold starts, especially in temperatures below 50°F (10°C)
• Glow plug indicator light staying illuminated longer than normal or flashing on the dashboard
• Excessive white or gray smoke from the exhaust during initial startup
• Rough idle for the first few minutes after a cold start
• ECM warning light activation with reduced engine performance in severe cases

Potential Causes

The most common technical causes for Code A-2 in used SK330-6E excavators include:

• Faulty glow plug relay due to contact wear or coil failure (common after 5,000+ operating hours)
• Failed individual glow plugs causing circuit resistance imbalance
• Damaged wiring harness at known rub points near the engine block or turbocharger heat shield
• Corroded connectors at the relay box or glow plug terminal connections from moisture intrusion
• ECM power supply issues affecting the pre-heating circuit's voltage regulation
• Intake air heater element failure (if equipped with grid heater system)

How to Troubleshoot and Fix Code A-2

Step 1: Visual Inspection Begin with a thorough inspection of the glow plug relay (typically located in the engine compartment fuse/relay box). Check all wiring harnesses running to the glow plugs for abraded insulation, especially where harnesses contact metal edges or hot engine components. Examine all electrical connectors for green corrosion or loose terminals—a prevalent issue in used machines.

Step 2: Electrical Testing Using a digital multimeter, test the glow plug relay operation. With the ignition on (pre-heat cycle active), you should measure battery voltage (12V) at the relay output terminal. Test individual glow plug resistance—typically 0.5-2.0 ohms for a functioning plug. Check the relay coil resistance (usually 70-90 ohms) and verify the ECM output signal to the relay (approximately 12V during pre-heat).

Step 3: Component Replacement If testing reveals failures, replace defective components using OEM or OEM-equivalent parts specifically rated for the SK330-6E. For used excavators, always replace connector terminals if corrosion is present, and apply dielectric grease to prevent future moisture issues. After repairs, clear the code using Kobelco diagnostic software or a compatible scan tool and perform multiple cold-start cycles to verify the fix.

Disclaimer: This guide provides general troubleshooting information. For used excavators with complex electrical issues or if you lack proper diagnostic tools, consult a certified Kobelco technician or heavy equipment diesel specialist to prevent misdiagnosis and unnecessary part replacement.