What is Komatsu PC210LC-10 Fault Code E-37?

Fault Code E-37 on the Komatsu PC210LC-10 indicates a malfunction in the engine speed sensor circuit, specifically detecting an abnormal signal or circuit failure in the primary engine RPM detection system. This diagnostic trouble code (DTC) is generated when the machine's Electronic Control Module (ECM) cannot receive proper engine speed data from the crankshaft position sensor or detects inconsistent readings that fall outside manufacturer-specified parameters.

This code is critical for the PC210LC-10's performance because the engine speed sensor provides essential data for fuel injection timing, load management, and hydraulic system coordination. When this sensor fails or sends erratic signals, the ECM cannot properly regulate engine performance, potentially leading to power loss, inefficient fuel consumption, or complete engine shutdown as a protective measure.

Common Symptoms

• Engine warning light illuminated on the dashboard with simultaneous loss of RPM gauge reading or erratic needle movement
• Automatic engine derating causing noticeable power reduction, especially under heavy load conditions during digging or lifting operations
• Rough idling or unexpected engine stalling, particularly during cold starts or when transitioning from idle to working RPM
• Hydraulic system performance issues including slower cycle times and reduced implement response due to engine-hydraulic coordination failure
• Intermittent engine shutdown without warning, requiring restart procedures and potentially displaying multiple fault codes

Potential Causes

The most common technical causes for E-37 on used PC210LC-10 excavators include:

• Crankshaft position sensor failure due to heat exposure, vibration damage, or internal component degradation after extended operating hours
• Damaged wiring harness near the sensor mounting location, particularly where the harness routes near the engine block—a known rub point on this model
• Corroded or loose electrical connectors at the sensor plug or ECM interface, common in machines operating in wet or corrosive environments
• Contaminated sensor face from metal debris, oil buildup, or coolant leaks affecting magnetic field detection
• ECM software glitches or internal ECM faults, though less common than sensor-related issues
• Damaged flywheel ring gear or missing teeth causing irregular signal patterns that trigger false fault codes

How to Troubleshoot and Fix Code E-37

Step 1: Visual Inspection and Code Verification Connect Komatsu diagnostic software (KOMTRAX Plus or compatible scan tool) to verify E-37 is active and check for additional codes. Inspect the crankshaft position sensor located on the engine's lower left side near the flywheel housing. Look for physical damage, loose mounting bolts, or excessive oil/debris buildup.

Step 2: Electrical Testing Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture intrusion—common issues in used excavators. Using a digital multimeter, measure sensor resistance (typically 150-300 ohms for Komatsu sensors, but verify against service manual specifications). Check wiring continuity from sensor to ECM connector pins, and inspect for harness damage along known friction points near engine mounts.

Step 3: Signal Testing and Component Replacement With the engine running (if possible), use diagnostic software to monitor live RPM signal data. Erratic readings or complete signal loss confirms sensor failure. Check the air gap between sensor and flywheel teeth (should be 0.5-1.5mm). For used machines, remove and clean the sensor face, inspect flywheel teeth for damage, and examine connector terminals for wear before replacement. If wiring and sensor test acceptable, ECM reprogramming or replacement may be necessary.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC210LC-10 service manual and consider professional diagnostic assistance for complex electrical issues or ECM-related repairs.