What is Hitachi ZX240N-5B Fault Code 14107-2?

Fault Code 14107-2 on the Hitachi ZX240N-5B excavator indicates an abnormal signal from the Intake Air Temperature (IAT) Sensor circuit, specifically a high voltage condition. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects a voltage reading above the manufacturer's specified threshold, typically caused by an open circuit, damaged sensor, or wiring fault in the intake air temperature monitoring system.

The IAT sensor plays a critical role in the ZX240N-5B's Isuzu engine management system by measuring incoming air temperature and sending this data to the ECM. The ECM uses this information to adjust fuel injection timing, air-fuel ratios, and optimize combustion efficiency. When Code 14107-2 appears, the engine defaults to a predetermined air temperature value, which can result in reduced performance, increased fuel consumption, and potential long-term engine damage if not addressed promptly.

Common Symptoms

• Check Engine Light (CEL) or malfunction indicator illuminated on the instrument panel
• Reduced engine power or lack of responsiveness during acceleration, particularly noticeable when cold starting
• Hard starting conditions in extreme temperatures due to improper fuel mixture calculations
• Increased black smoke from the exhaust, indicating rich fuel mixture compensation
• Higher than normal fuel consumption as the ECM operates in fail-safe mode with default parameters

Potential Causes

The most common causes of Code 14107-2 on used ZX240N-5B excavators include:

• Failed IAT sensor due to age-related degradation or contamination from oil vapors in the intake system
• Open circuit in the sensor wiring harness, particularly at harness rub points near the air intake manifold and engine firewall
• Corroded or loose connector pins at the IAT sensor connector—common in machines exposed to wet or dusty environments
• Damaged wiring insulation from rodent activity, especially on excavators stored outdoors for extended periods
• ECM internal fault (rare, but possible in high-hour used machines)
• Poor ground connection affecting the sensor's reference voltage circuit

How to Troubleshoot and Fix Code 14107-2

Step 1: Visual Inspection Begin by locating the IAT sensor on the intake air duct between the air filter and turbocharger inlet. Inspect the sensor connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the wiring harness routing for any signs of chafing against metal edges, particularly where it passes near the alternator bracket—a known wear point on this model.

Step 2: Electrical Testing Disconnect the IAT 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 (consult your service manual for exact specifications). If the reading shows infinite resistance (open circuit), the sensor has failed and requires replacement.

Step 3: Circuit Voltage Check With the ignition on and sensor disconnected, check for 5-volt reference voltage at the harness connector using your multimeter. If voltage is present, test continuity between the sensor ground wire and chassis ground. No voltage indicates a harness break or ECM fault; trace the wiring back to the ECM connector, inspecting for damage.

Step 4: Replacement and Verification Replace the faulty component (sensor or repair damaged wiring), ensuring all connections are clean and properly sealed. Use dielectric grease on connector pins to prevent future corrosion. Clear the fault code using Hitachi diagnostic software (Dr.EX) or a compatible scan tool, then operate the machine through a complete warm-up cycle to verify the repair.

Disclaimer: This guide provides general troubleshooting information. Always consult the Hitachi ZX240N-5B service manual for exact specifications and procedures. If you lack experience with heavy equipment electrical systems, consult a certified Hitachi technician to avoid improper diagnosis or safety hazards.