What is Hitachi ZX170W-3 Fault Code 14106-2?

Fault Code 14106-2 indicates a malfunction in the Exhaust Gas Recirculation (EGR) valve position sensor circuit, specifically a signal voltage abnormality or sensor range/performance issue. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects that the EGR valve position feedback signal is either out of specification, erratic, or not corresponding to the commanded valve position.

The EGR system is critical on the ZX170W-3's emission-controlled diesel engine, as it recirculates a portion of exhaust gases back into the combustion chamber to reduce nitrogen oxide (NOx) emissions. When Code 14106-2 appears, the ECM cannot accurately verify EGR valve movement, potentially causing the engine to operate in derate mode or fail emissions standards. For used excavators, this fault is particularly common due to carbon buildup, sensor wear, and harness deterioration from heat and vibration exposure.

Common Symptoms

When Fault Code 14106-2 is active on your Hitachi ZX170W-3, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Engine power reduction (derate mode) limiting machine performance to protect emissions systems
• Rough idling or irregular engine response during low-load operations
• Increased black smoke from the exhaust due to altered combustion parameters
• Poor fuel economy as the ECM compensates for unverified EGR operation

Potential Causes

Several mechanical and electrical issues can trigger this fault code on used excavators:

• EGR valve position sensor failure due to heat degradation or internal component wear
• Carbon buildup on the EGR valve stem preventing smooth operation and accurate position feedback
• Damaged wiring harness or corroded connectors in the EGR sensor circuit (common wear point near the exhaust manifold)
• Faulty ECM or corrupted calibration data (less common but possible in high-hour machines)
• Poor electrical ground connections at the sensor or ECM mounting points
• Contaminated sensor contacts from oil mist or coolant intrusion in the engine bay

How to Troubleshoot and Fix Code 14106-2

Step 1: Visual Inspection Begin by inspecting the EGR valve assembly and position sensor wiring harness. Look for heat damage, abrasion points where the harness contacts the engine block, melted insulation, or corroded connector pins. On used excavators, harness chafing near the valve cover is a known failure point. Clean all connector contacts with electrical contact cleaner and ensure proper seating.

Step 2: Electrical Testing Using a digital multimeter, check the sensor supply voltage at the connector (should be approximately 5 volts from the ECM). Test sensor ground continuity (should be less than 1 ohm to chassis ground). Measure the position sensor signal voltage while manually operating the EGR valve—it should sweep smoothly between 0.5-4.5 volts. Erratic readings indicate sensor replacement is necessary.

Step 3: Mechanical Verification Remove the EGR valve and inspect for carbon deposits restricting valve movement. Clean the valve thoroughly with EGR cleaner or replace if the stem is pitted or seized. Verify smooth mechanical operation before reinstallation. Check that the valve moves freely through its full range when powered.

Step 4: Advanced Diagnostics Connect Hitachi diagnostic software (Dr.EX or equivalent) to perform active tests, commanding the EGR valve to specific positions while monitoring actual position feedback. Compare commanded vs. actual values—discrepancies exceeding 10% indicate sensor or valve mechanical issues.

Step 5: Final Verification After repairs, clear the fault code using diagnostic software, perform a regeneration cycle if required, and road-test the machine under load. Monitor for code recurrence over several operating hours.

---

Disclaimer: This guide provides general troubleshooting information for Fault Code 14106-2. Always consult the official Hitachi service manual for your specific machine serial number and software version. If you lack proper diagnostic tools or experience with emission control systems, seek assistance from a certified Hitachi technician to avoid costly misdiagnosis or safety hazards.