What is Hitachi ZX350LCK-5G Fault Code 14105-2?

Fault Code 14105-2 indicates a malfunction in the exhaust gas recirculation (EGR) valve position sensor circuit, specifically a voltage signal that is out of the normal operating range. This code is triggered when the engine control module (ECM) detects that the EGR valve position feedback does not match the commanded position, typically due to abnormal voltage readings from the sensor.

The EGR system is critical for emissions control on the Hitachi ZX350LCK-5G excavator, recirculating a portion of exhaust gases back into the combustion chamber to reduce nitrogen oxide (NOx) emissions. When the position sensor fails to provide accurate feedback, the ECM cannot properly regulate EGR flow, potentially leading to increased emissions, reduced fuel efficiency, and engine performance issues. On used excavators, this code often appears due to sensor degradation or wiring problems from years of exposure to heat and vibration.

Common Symptoms

• Check engine light or diagnostic warning lamp illuminated on the instrument cluster
• Engine power derate or reduced throttle response, especially under heavy loads
• Rough idling or unstable engine operation at low RPMs
• Increased black or white smoke from the exhaust during operation
• Poor fuel economy compared to normal operating conditions

Potential Causes

The most common technical reasons for Code 14105-2 on used ZX350LCK-5G excavators include:

• Failed EGR valve position sensor due to carbon buildup, heat damage, or internal component wear
• Damaged wiring harness between the sensor and ECM, particularly at flex points near the engine block where vibration causes wire chafing
• Corroded or loose electrical connectors at the sensor or ECM connection points—extremely common on older machines
• Faulty ECM (less common) with internal circuit board issues affecting sensor signal processing
• Shorted or open circuit in the sensor supply voltage or ground wires
• Carbon deposits on the EGR valve preventing proper movement and accurate position feedback

How to Troubleshoot and Fix Code 14105-2

Step 1: Visual Inspection Begin by inspecting the EGR valve position sensor and its wiring harness. Look for obvious damage, corrosion on connector pins, or wire insulation wear. On used excavators, pay special attention to harness routing near hot exhaust components and moving parts where abrasion commonly occurs. Clean all electrical connectors with contact cleaner and ensure tight connections.

Step 2: Sensor Circuit Testing Using a digital multimeter, check the sensor supply voltage (typically 5 volts) at the connector with the ignition on. Measure the sensor signal wire voltage while manually moving the EGR valve (if accessible). The voltage should change smoothly between approximately 0.5V and 4.5V. Also verify ground circuit continuity with less than 1 ohm resistance to chassis ground.

Step 3: Sensor and Valve Inspection Remove the EGR valve assembly and inspect for heavy carbon buildup that could restrict valve movement. Clean thoroughly with appropriate EGR cleaner. If the position sensor shows erratic voltage readings or fails to change voltage smoothly, replace it. For used machines, consider replacing the entire EGR valve assembly if it has over 5,000 operating hours.

Step 4: Advanced Diagnostics If basic checks pass, use Hitachi Dr.EX diagnostic software or compatible scan tool to monitor live sensor data and command EGR valve positions. Compare commanded versus actual positions. Check for intermittent connection issues by wiggling harnesses while monitoring data.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and seek professional assistance from certified technicians for complex electrical diagnostics or emissions system repairs.