What is Hitachi ZX330-5G Fault Code 20106-2?

Fault Code 20106-2 on the Hitachi ZX330-5G excavator indicates a malfunction in the Engine Speed Sensor (Crankshaft Position Sensor) circuit, specifically detecting an abnormal signal or intermittent connection. This code is triggered when the Electronic Control Module (ECM) receives irregular voltage patterns or no signal from the crankshaft position sensor, which monitors engine rotational speed and piston position.

This fault is critical because the engine speed sensor provides essential data for fuel injection timing, engine governor control, and overall power management. Without accurate crankshaft position information, the ZX330-5G's Isuzu engine cannot optimize combustion cycles, leading to performance degradation or complete shutdown to prevent engine damage.

Common Symptoms

• Engine cranks but fails to start or experiences prolonged cranking before ignition
• Intermittent stalling during operation, especially at idle or under load
• Loss of engine power or failure to reach rated RPM (approximately 2,000 RPM on this model)
• Warning lights illuminate on the instrument cluster, specifically the engine diagnostic indicator
• Rough idling or irregular engine operation with noticeable vibration

Potential Causes

The most common causes for Code 20106-2 on used ZX330-5G excavators include:

• Worn or damaged crankshaft position sensor due to heat exposure and vibration over extended operating hours
• Corroded or loose connector pins at the sensor harness connection point near the flywheel housing
• Damaged wiring harness from rubbing against the engine block or frame rails—a known wear point on this model series
• Contaminated sensor face from oil leaks, metal debris, or excessive dirt buildup affecting magnetic field detection
• Faulty ECM (less common) with internal circuit board degradation in higher-hour machines
• Improper air gap between the sensor tip and reluctor ring on the crankshaft

How to Troubleshoot and Fix Code 20106-2

Step 1: Visual Inspection Begin by accessing the crankshaft position sensor located on the lower left side of the engine block near the flywheel. Inspect the sensor connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the wiring harness routing for signs of chafing against metal surfaces—a frequent issue after 5,000+ operating hours.

Step 2: Electrical Testing Using a digital multimeter, measure the sensor's resistance between the two signal terminals. Specifications typically range between 190-250 ohms at room temperature (consult your service manual). Check supply voltage at the connector with the key on, engine off—you should read approximately 8-12 volts. Inspect for intermittent connections by wiggling the harness while monitoring resistance.

Step 3: Sensor and Air Gap Verification Remove the sensor and clean the sensing tip with electrical contact cleaner. Verify the air gap between the sensor and reluctor ring is within 0.5-1.2mm using feeler gauges. Replace the sensor if resistance values are out of specification or if physical damage is evident.

Step 4: Harness and ECM Check Trace the wiring from the sensor to the ECM connector (located behind the operator cab), checking for continuity and shorts to ground. For persistent codes after sensor replacement, ECM reprogramming or replacement may be necessary—use Hitachi's Dr.EX diagnostic software for advanced troubleshooting.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and seek professional diesel technician assistance for complex electrical diagnostics or ECM-related repairs.