What is Hitachi ZX670LC-5A Fault Code 20107-2?

Fault Code 20107-2 indicates a malfunction in the fuel injection system's high-pressure circuit, specifically a pressure deviation error in the common rail fuel delivery system. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects that actual fuel rail pressure deviates significantly from the commanded target pressure during engine operation.

In the Hitachi ZX670LC-5A's Isuzu engine, the common rail fuel system maintains precise fuel delivery at extremely high pressures (typically 1,600-2,000 bar). When Code 20107-2 activates, it signals that the fuel rail pressure sensor is reporting values outside acceptable parameters, or the supply control valve (SCV) cannot properly regulate pressure. This is critical because improper fuel pressure directly affects combustion efficiency, engine power output, and can lead to expensive injector damage if left unaddressed.

Common Symptoms

• Engine power loss or derate mode, with the machine limiting maximum RPM to protect internal components
• Rough idling or unstable engine operation, particularly noticeable during cold starts
• Black or white exhaust smoke indicating incomplete combustion due to fuel delivery issues
• Warning lamp illumination on the instrument cluster, often accompanied by audible alerts
• Difficulty starting or extended cranking time, especially after the machine has been sitting idle

Potential Causes

The most common technical failures triggering Code 20107-2 on used ZX670LC-5A excavators include:

• Fuel rail pressure sensor failure due to internal diaphragm degradation or contaminated fuel exposure
• Supply Control Valve (SCV) sticking or electrical fault, often caused by carbon buildup in high-hour machines
• Fuel contamination (water or particulates) compromising system calibration
• Wiring harness damage at known rub points near the engine block mounting brackets or along the chassis rail
• High-pressure fuel pump wear, common in machines exceeding 8,000 operating hours
• ECM calibration drift or corrupted software in older control modules

How to Troubleshoot and Fix Code 20107-2

Step 1: Connect Diagnostic Software Use Hitachi Dr.EX diagnostic software or compatible scan tool to retrieve live data. Monitor actual vs. commanded fuel rail pressure values at idle and under load. Deviations exceeding 200 bar indicate active system problems.

Step 2: Inspect Fuel Rail Pressure Sensor Located on the common rail assembly, check the 3-pin connector for corrosion—a common issue in used excavators exposed to moisture. Using a digital multimeter, verify sensor output voltage (typically 0.5-4.5V range). Resistance should measure approximately 120-150 ohms at room temperature. For used machines, carefully inspect connector seals and wire insulation for cracks.

Step 3: Test Supply Control Valve (SCV) The SCV, mounted on the high-pressure pump, regulates fuel flow. Check electrical resistance across SCV terminals (should read 2-4 ohms). Inspect wiring for harness abrasion against engine mounts—a known wear point on ZX670LC-5A models. Remove and inspect for carbon deposits if electrical tests pass.

Step 4: Verify Fuel Quality and Filter Condition Drain fuel samples from the tank's lowest point. Check for water contamination using water-detection paste. Replace primary and secondary fuel filters, ensuring proper bleeding procedures to eliminate air.

Step 5: Perform High-Pressure Pump Output Test If previous steps don't resolve the code, connect a mechanical fuel pressure gauge to the test port. Compare readings against Hitachi specifications (consult service manual). Pump wear is likely if pressure cannot reach 1,400+ bar.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number. Complex fuel system repairs should be performed by certified technicians with proper diagnostic equipment and safety training.