What is Hitachi ZX210-5B Fault Code 14106-2?

Fault Code 14106-2 indicates an Engine Speed Sensor Circuit Malfunction - specifically a signal abnormality or intermittent connection issue in the crankshaft position sensor system. This diagnostic trouble code (DTC) is triggered when the engine control module (ECM) detects irregular or missing signals from the crankshaft position sensor that monitors engine rotational speed and timing.

On the Hitachi ZX210-5B, this sensor is critical for proper fuel injection timing, engine synchronization, and overall performance monitoring. The ECM relies on this data to control fuel delivery, adjust injection pressure, and maintain optimal combustion efficiency. When this code activates, the machine's onboard diagnostics detect either voltage irregularities, signal dropout, or circuit resistance problems that prevent accurate engine speed readings.

This is particularly problematic in used excavators where sensor degradation, wiring harness deterioration, and connector corrosion are common issues affecting signal integrity.

Common Symptoms

• Engine cranks but struggles to start or experiences extended cranking periods before firing
• Intermittent engine stalling during operation, especially during idle or low-load conditions
• Engine warning light illuminated on the instrument panel (amber or red depending on severity)
• Loss of power or performance derate as the ECM enters failsafe mode to protect the engine
• Rough idle or misfiring due to improper fuel injection timing caused by incorrect speed signal data

Potential Causes

Crankshaft position sensor failure is the most common culprit, especially on machines with over 5,000 operating hours. The sensor's magnetic pickup can degrade or the internal components can fail from heat exposure and vibration.

Damaged or corroded wiring harness between the sensor and ECM—particularly at known rub points near the engine mounting brackets or along the right side of the engine block where the harness routes.

Loose or corroded electrical connectors at the sensor terminal or ECM connection points. Used excavators frequently experience moisture intrusion in these connectors, creating intermittent contact.

Damaged reluctor ring (toothed wheel) on the crankshaft that the sensor reads. Physical damage or excessive carbon buildup can disrupt the magnetic field.

ECM internal fault or corrupted software, though this is less common than sensor or wiring issues.

How to Troubleshoot and Fix Code 14106-2

Step 1: Visual Inspection and Connector Check

Begin by locating the crankshaft position sensor on the transmission bell housing (driver's side, lower section). Inspect the sensor harness for obvious damage, abrasion, or pinch points. Disconnect the sensor connector and examine both male and female terminals for corrosion, bent pins, or moisture. Clean with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Sensor Resistance and Signal Testing

Using a digital multimeter, measure the sensor's resistance. The crankshaft position sensor should typically read between 150-300 ohms (consult your service manual for exact specifications). Readings outside this range indicate sensor failure. Next, check for circuit continuity between the sensor connector and the ECM harness connector—there should be less than 1 ohm resistance on signal wires.

Step 3: Dynamic Signal Testing with Diagnostic Software

Connect Hitachi Dr.EX diagnostic software or an equivalent OEM scanner to monitor live sensor data. Crank the engine and observe whether the ECM receives consistent RPM signals. Erratic readings or complete signal loss during cranking confirms sensor or circuit malfunction. For used excavators, pay special attention to intermittent signal dropout patterns that suggest failing connections rather than complete sensor death.

Step 4: Inspect Reluctor Ring and Air Gap

If the sensor tests within specifications, remove it and visually inspect the reluctor ring on the flywheel for damage, missing teeth, or excessive debris buildup. Clean thoroughly with brake cleaner. Verify the air gap between sensor tip and reluctor ring is within specification (typically 0.5-1.5mm). Improper gap can cause weak signal generation.

Step 5: Replacement and Verification

Replace the crankshaft position sensor with a genuine Hitachi part or high-quality aftermarket equivalent. After installation, clear fault codes using diagnostic software and perform a test run under load. Monitor for code recurrence over several operating cycles.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hitachi service manual for your specific machine serial number and follow proper safety procedures. If unfamiliar with electrical diagnostics or ECM systems, consult a certified Hitachi technician to prevent further damage to your equipment.