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

Fault Code 14106-2 on the Hitachi ZX870LC-5A indicates a circuit malfunction in the Engine Oil Pressure Sensor, specifically a low voltage or open circuit condition detected by the Engine Control Module (ECM). This diagnostic trouble code (DTC) triggers when the ECM receives a signal below the expected voltage threshold from the oil pressure sensor circuit, typically below 0.5 volts when normal operating range should be 0.5-4.5 volts.

This code is critical for the ZX870LC-5A's Isuzu AH-6WG1X engine because inadequate oil pressure monitoring can prevent early detection of lubrication system failures. In severe cases, the ECM may initiate engine derate or shutdown protocols to prevent catastrophic engine damage. For used excavators, this fault often indicates sensor degradation or harness issues rather than actual oil pressure problems.

Common Symptoms

• Engine warning light illuminated on the instrument cluster with possible audible alarm
• Power derate mode activated, limiting engine RPM to 1,200-1,500 range to protect components
• Intermittent fault code appearance that may clear and return, especially during cold starts or machine vibration
• Oil pressure gauge reading erratically or showing zero pressure despite engine running normally
• Delayed engine startup as the ECM performs extended diagnostic checks before allowing operation

Potential Causes

The most common causes for Code 14106-2 on used ZX870LC-5A excavators include:

• Oil pressure sensor internal failure due to age, heat cycling, or contamination (common failure point after 8,000+ hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at the harness routing point near the engine oil filter housing where friction against the frame occurs
• Corroded or loose electrical connectors at the sensor or ECM interface, especially on machines operated in wet or coastal environments
• ECM internal circuit board degradation (less common but possible in high-hour machines)
• Broken or chafed wires in the engine harness from improper previous repairs or excessive engine vibration
• Low battery voltage causing insufficient sensor excitation voltage

How to Troubleshoot and Fix Code 14106-2

Step 1: Visual Inspection and Connector Check Begin by inspecting the oil pressure sensor located on the driver's side of the engine block near the oil filter assembly. Disconnect the sensor connector and examine both male and female terminals for corrosion, bent pins, or oil contamination. Clean contacts with electrical contact cleaner and apply dielectric grease. For used excavators, check the harness routing from sensor to ECM for visible wear, especially where the harness contacts frame members or passes near hot exhaust components.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, perform a continuity test on the sensor circuit. With the connector disconnected at both the sensor and ECM, check for continuity between the signal wire terminals—you should read infinite resistance (open circuit). Then check each wire to ground; any reading below 10k ohms indicates a short to ground. Measure the reference voltage from the ECM connector (sensor disconnected); you should see approximately 5 volts on the signal wire. If voltage is absent, suspect ECM issues or a broken wire.

Step 3: Sensor Replacement and Verification If wiring tests pass, replace the oil pressure sensor with a genuine Hitachi part (part number 8-98043814-0). After installation with proper torque (typically 15-20 ft-lbs), clear the fault code using Hitachi Dr.EX diagnostic software or a compatible J1939 scan tool. Run the engine through multiple temperature cycles and load conditions to verify the repair. For used machines, consider replacing the entire sensor-to-ECM harness section if the machine has over 12,000 operating hours, as preventive maintenance against future intermittent faults.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hitachi service manual for your specific machine serial number and seek professional diagnostic assistance if unfamiliar with electrical systems or high-pressure components.