What is Hitachi ZX870LC-5A Fault Code 14106-2?

Fault Code 14106-2 indicates a malfunction in the engine oil pressure sensor circuit, specifically a voltage signal that is too low or out of range. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage reading from the oil pressure sensor, typically below the manufacturer's specified threshold of approximately 0.5 volts.

In the Hitachi ZX870LC-5A equipped with the Isuzu 6WG1X engine, this code directly impacts the ECM's ability to monitor critical engine lubrication. The oil pressure sensor provides real-time data that protects internal engine components from catastrophic damage due to insufficient lubrication. When this circuit fails, the machine may enter a protective derate mode to prevent engine seizure, significantly reducing operational productivity on job sites.

Common Symptoms

• Engine warning lamp illuminated on the instrument panel with reduced engine power output
• Automatic engine derate limiting RPM to approximately 1,200-1,500 range, preventing normal working speeds
• Audible alarm sounding intermittently or continuously from the operator cabin
• Erratic or zero oil pressure readings displayed on the monitor, even when engine oil level is correct
• Difficulty starting or the engine entering limp mode immediately after startup in severe cases

Potential Causes

The most common technical failures causing Code 14106-2 on used ZX870LC-5A excavators include:

• Failed oil pressure sensor due to internal element degradation (common after 8,000+ operating hours)
• Damaged wiring harness between the sensor and ECM, particularly at harness routing points near the engine block where vibration causes wire chafing
• Corroded or loose electrical connectors at the sensor plug, especially on machines operated in high-moisture or marine environments
• Short circuit to ground in the sensor signal wire caused by insulation breakdown
• ECM internal circuit failure (rare, but possible in high-hour machines with electrical system exposure to contaminants)
• Low engine oil level causing actual low pressure, triggering sensor voltage drop

How to Troubleshoot and Fix Code 14106-2

Step 1: Visual Inspection and Voltage Testing Begin by checking engine oil level and condition. Locate the oil pressure sensor on the lower left side of the engine block. Inspect the three-pin connector for corrosion, bent pins, or oil contamination. Using a digital multimeter, backprobe the sensor signal wire (typically green/white) with the ignition on, engine off. You should read approximately 0.8-1.2 volts. Readings below 0.3 volts indicate a circuit problem.

Step 2: Sensor and Harness Testing Disconnect the sensor and measure resistance across the sensor terminals. A functional sensor shows 50-150 ohms at room temperature. Check for continuity to ground on the signal wire with the sensor disconnected—any continuity indicates a short circuit. On used excavators, carefully inspect the harness routing along the engine valley where the wiring loom contacts metal brackets, a known wear point on this model.

Step 3: Component Replacement and Verification If the sensor tests faulty, replace it with a genuine Hitachi part (P/N 8-98151839-0). Apply dielectric grease to connector pins before reassembly. Clear codes using Dr.EX diagnostic software or a compatible J1939 scan tool. Run the engine and monitor live data to confirm oil pressure readings stabilize at 290-430 kPa at idle. For persistent codes after sensor replacement, perform ECM voltage supply checks (should be 4.8-5.2V reference voltage) or consult wiring diagrams for harness continuity testing.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and consult qualified diesel technicians for complex electrical diagnostics or warranty concerns.