What is Kobelco SK200-6 Fault Code D-2?

Kobelco SK200-6 Fault Code D-2 indicates a malfunction in the engine revolution sensor circuit, specifically detecting an abnormal signal or loss of communication between the revolution sensor and the Engine Control Module (ECM). This code relates to the crankshaft position sensor system, which monitors engine speed and crankshaft positioning for proper fuel injection timing and engine management.

This fault is critical because the revolution sensor provides real-time data that the ECM uses to control fuel delivery, injection timing, and overall engine performance. On the SK200-6 model equipped with Isuzu or Hino diesel engines, this sensor failure can lead to starting difficulties, rough running, or complete engine shutdown. For used excavators, this code often appears due to sensor degradation, wiring harness damage from vibration, or connector corrosion accumulated over thousands of operating hours.

Common Symptoms

When Code D-2 is active on your Kobelco SK200-6, you may experience:

• Engine cranks but fails to start or starts with extreme difficulty and excessive cranking time
• Intermittent stalling during operation, especially under load or at idle
• Rough idling with noticeable engine vibration and inconsistent RPM
• Check engine light illuminated on the instrument panel with possible audible warning alarm
• Loss of power or engine running in limp mode with reduced throttle response

Potential Causes

The most common technical causes for Code D-2 on used SK200-6 excavators include:

• Failed revolution sensor (crankshaft position sensor) due to internal component breakdown or heat damage
• Damaged wiring harness between the sensor and ECM, particularly at known rub points near the engine bell housing and along the frame rail
• Corroded or loose electrical connectors at the sensor plug or ECM harness connection
• Broken or damaged sensor mounting causing improper air gap between sensor and flywheel ring gear
• ECM internal fault or poor ground connections affecting signal processing
• Flywheel ring gear damage with missing or damaged teeth preventing proper sensor readings

How to Troubleshoot and Fix Code D-2

Step 1: Visual Inspection Locate the revolution sensor mounted on the engine bell housing near the flywheel. Inspect the sensor body for physical damage, oil contamination, or loose mounting bolts. Check the wiring harness from sensor to ECM for abrasion, cuts, or melted insulation—pay special attention to areas where the harness contacts frame rails or passes near hot exhaust components.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals. Typical readings should be 150-300 ohms (consult your service manual for exact specifications). Test continuity of the wiring harness from the sensor connector to the ECM pins. Check for voltage supply (typically 5-12V reference voltage) from the ECM with ignition on, engine off.

Step 3: Air Gap and Signal Testing Verify the air gap between the sensor tip and flywheel ring gear teeth using feeler gauges (typically 0.5-1.5mm specification). With the sensor connected, use an oscilloscope or AC voltmeter to check for signal generation while manually rotating the engine. The sensor should produce an alternating voltage signal as flywheel teeth pass the sensor tip.

Step 4: Component Replacement For used excavators, if electrical tests pass but the code persists, inspect connector terminals for corrosion or terminal spread—clean with electrical contact cleaner and apply dielectric grease. Replace the revolution sensor if resistance is out of specification or no signal is generated. After replacement, clear codes using Kobelco diagnostic software or a compatible scanner and perform a test run under load.

Important for Used Equipment: Before replacing expensive components, thoroughly inspect all connectors and harnesses for damage common in aged machinery. Many D-2 codes result from simple connector corrosion or harness chafing rather than actual sensor failure.

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Disclaimer: This guide provides general diagnostic information for Kobelco SK200-6 excavators. Always consult the manufacturer's service manual for exact specifications and procedures. If you're unfamiliar with electrical diagnostics or engine systems, seek assistance from a qualified heavy equipment technician to prevent misdiagnosis or equipment damage.