What is Hitachi ZX200LC-5G Fault Code 14105-2?

Fault Code 14105-2 indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition in the sensor wiring harness. This code is triggered when the Engine Control Module (ECM) receives a voltage reading outside the normal operating range (typically above 4.5V) from the coolant temperature sensor located on the engine block.

This fault is critical for the ZX200LC-5G because the ECM relies on accurate coolant temperature data to optimize fuel injection timing, control engine idle speed, and prevent overheating damage. When this sensor circuit fails, the ECM operates in a default "limp mode" using pre-programmed temperature assumptions, which can lead to poor fuel economy, excessive emissions, and potential engine damage if actual overheating occurs undetected.

Common Symptoms

• Check Engine Light illuminated on the instrument panel with reduced engine performance
• Engine running rough or hunting at idle due to incorrect fuel mapping
• Difficulty starting when the engine is cold, as the ECM cannot determine proper cold-start enrichment
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Possible engine derate or power reduction to protect components from assumed overheating conditions

Potential Causes

The most common causes of fault code 14105-2 on used ZX200LC-5G excavators include:

• Open circuit in the coolant temperature sensor wiring due to harness chafing against the engine block or hydraulic lines (known wear point near the fuel filter assembly)
• Failed coolant temperature sensor with internal open circuit, common after 5,000+ operating hours
• Corroded or loose connector pins at the sensor plug, especially on machines operated in wet or marine environments
• Damaged ECM wiring harness from rodent activity or improper previous repairs
• Rare: ECM internal failure affecting the 5V reference voltage supply circuit

How to Troubleshoot and Fix Code 14105-2

Step 1: Visual Inspection Locate the coolant temperature sensor on the left side of the engine block near the thermostat housing. Inspect the wiring harness for obvious damage, abrasion points where the harness contacts metal surfaces, or melted insulation. Check the connector for corrosion, bent pins, or moisture intrusion—clean with electrical contact cleaner if needed.

Step 2: Sensor Resistance Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms. Compare readings to the manufacturer's temperature-resistance chart. If resistance reads infinite (open circuit) or zero, replace the sensor.

Step 3: Wiring Harness Continuity Check With the sensor disconnected, measure continuity between the sensor connector pins and the ECM connector (pins specified in the service manual). Also check for shorts to ground. Resistance should be less than 5 ohms for continuity and infinite for insulation. On used excavators, pay special attention to harness routing—replace any sections with worn insulation.

Step 4: ECM Reference Voltage Verification Turn the ignition to ON (engine off), and measure voltage at the sensor connector. You should see approximately 5V reference voltage from the ECM. If voltage is absent or incorrect, suspect ECM issues or damaged power supply wiring.

Step 5: Clear Code and Test After repairs, use Hitachi diagnostic software (Dr.EX) or a compatible scanner to clear the fault code. Run the engine through temperature cycles and monitor for code recurrence.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues or if you lack proper testing equipment.