Komatsu PC200-10 Fault Code S-2: Complete Diagnostic Guide

What is Komatsu PC200-10 Fault Code S-2?

Fault Code S-2 on the Komatsu PC200-10 indicates a malfunction in the engine revolution sensor (crankshaft position sensor) circuit. This code is triggered when the Engine Control Module (ECM) detects an abnormal signal or complete signal loss from the crankshaft position sensor, which monitors engine speed and crankshaft positioning.

This sensor is critical for the PC200-10's SAA6D107E-1 engine, as it provides essential data for fuel injection timing, engine speed control, and overall combustion management. Without accurate crankshaft position data, the ECM cannot properly regulate engine performance, potentially leading to starting issues or unexpected shutdowns.

Common Symptoms

When Code S-2 is active on your Komatsu PC200-10, operators typically experience:

• Engine fails to start or cranks without firing
• Sudden engine shutdown during operation with no warning
• Monitor panel displays S-2 error code with warning light illumination
• Erratic engine RPM fluctuations or unstable idle before complete failure
• Loss of engine power or hesitation during acceleration under load

Potential Causes

The most common technical causes for S-2 on used PC200-10 excavators include:

• Crankshaft position sensor failure due to heat exposure or internal component degradation (common after 6,000+ operating hours)
• Damaged or corroded wiring harness at the sensor connector, especially where harness passes near the engine block
• Broken signal wire from vibration or rubbing against the flywheel housing (known issue on older units)
• Air gap misalignment between sensor tip and reluctor wheel caused by mounting bolt loosening
• ECM internal circuit failure affecting sensor signal processing (rare but possible in high-hour machines)
• Contamination buildup on sensor tip from oil leaks or metallic debris

How to Troubleshoot and Fix Code S-2

Step 1: Visual Inspection Locate the crankshaft position sensor on the flywheel housing (driver's side, lower engine section). Inspect the wiring harness for visible damage, worn insulation, or oil contamination. Check connector pins for corrosion or bent terminals—common in used excavators operating in harsh environments.

Step 2: Sensor Air Gap Verification Verify the air gap between the sensor tip and reluctor wheel is within specification (typically 0.5-1.5mm). Use a feeler gauge to measure. On used machines, check mounting bolt torque as vibration often loosens them over time.

Step 3: Electrical Testing Using a digital multimeter, measure sensor resistance (typically 190-250 ohms at room temperature). Check signal voltage at the ECM connector while cranking—should show AC voltage pulses. Test harness continuity from sensor to ECM pins and verify less than 1 ohm resistance.

Step 4: Signal Output Testing Connect Komatsu KOMTRAX diagnostic software or compatible scan tool to monitor live sensor data during cranking. No signal indicates sensor failure; intermittent signal suggests wiring issues.

Step 5: Component Replacement Replace the crankshaft position sensor if testing confirms failure (Komatsu part 6754-81-3130). For used excavators, always replace the connector pigtail simultaneously to prevent future corrosion issues. Clear codes and perform cranking test.

Disclaimer: This guide provides general troubleshooting steps. Always consult the official Komatsu PC200-10 service manual and consider professional diagnostic assistance for complex electrical issues.