What is Hitachi ZX210LCK-5G Fault Code 16607-2?

Fault Code 16607-2 on the Hitachi ZX210LCK-5G excavator indicates a malfunction in the DEF (Diesel Exhaust Fluid) pressure sensor circuit, specifically a voltage signal that is too low or out of range. This code is part of Hitachi's emissions control system monitoring and relates directly to the Selective Catalytic Reduction (SCR) aftertreatment system that reduces NOx emissions.

The DEF pressure sensor monitors the pressure of urea solution being injected into the exhaust stream. When the Engine Control Module (ECM) detects voltage readings below the manufacturer's specified threshold (typically below 0.5V), it triggers this fault code. This is critical for the ZX210LCK-5G because the SCR system is essential for meeting Tier 4 Final emissions standards, and prolonged malfunction can result in engine derate or prevent the machine from starting after shutdown.

Common Symptoms

• Amber or red DEF warning light illuminated on the instrument cluster
• Engine power derate after a specific number of operating hours (usually progressive reduction)
• "Check Engine" or malfunction indicator lamp (MIL) active on dashboard
• DEF system error messages displayed on the monitor screen
• Reduced hydraulic performance due to engine power limitations in severe cases

Potential Causes

The most common technical causes for Code 16607-2 on used Hitachi excavators include:

• Failed DEF pressure sensor due to crystallized urea contamination or internal component degradation
• Damaged or corroded wiring harness between the sensor and ECM, especially at connection points near the exhaust system where heat cycles cause wire insulation breakdown
• Poor electrical connections at the sensor connector—corrosion from DEF exposure is common in older machines
• Low system voltage from weak batteries or failing alternator affecting sensor reference voltage
• ECM internal fault (rare, but possible in high-hour used machines)
• Contaminated or frozen DEF causing sensor mechanical binding or electrical interference

How to Troubleshoot and Fix Code 16607-2

Step 1: Visual Inspection Begin by inspecting the DEF pressure sensor location (mounted on the DEF supply line near the dosing module). Check for physical damage, DEF leaks, or crystallization around the sensor body. On used excavators, examine the wiring harness for abrasion points where it contacts frame members or exhaust components—this is a known wear point on ZX-5G series machines.

Step 2: Electrical Testing Using a digital multimeter, disconnect the DEF pressure sensor connector and check for supply voltage (should be approximately 5V reference) and ground continuity at the harness side. Measure sensor resistance according to Hitachi specifications (typically 1,000-3,000 ohms at room temperature). Check for voltage drop along the harness by backprobing connections while wiggling wires to identify intermittent faults.

Step 3: Component Testing and Replacement Connect Hitachi Dr.EX diagnostic software or compatible scan tool to read live sensor data. Compare actual pressure readings with expected values during DEF system priming. If voltage remains below 0.5V with good harness connections, replace the DEF pressure sensor with a genuine Hitachi part. For used equipment, always clean connector pins with electrical contact cleaner and apply dielectric grease before reconnection to prevent future corrosion. Clear codes and perform a DEF system prime cycle to verify repair.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific serial number and seek professional diagnostic assistance for complex electrical or emissions system issues. Improper repairs may affect emissions compliance and warranty coverage.