What is Hitachi ZX670LC-5A Fault Code 14103-2?

Fault Code 14103-2 indicates a malfunction in the Engine Oil Pressure Sensor Circuit - Voltage Low condition on the Hitachi ZX670LC-5A excavator. This code triggers when the Engine Control Module (ECM) detects an abnormally low voltage signal from the oil pressure sensor circuit, typically below 0.5 volts.

The oil pressure sensor is a critical component in the Isuzu 6WG1X engine used in the ZX670LC-5A, constantly monitoring lubricating oil pressure and sending voltage signals to the ECM. When voltage reads too low, it indicates either genuine low oil pressure, a failing sensor, or compromised wiring—all of which can lead to catastrophic engine damage if ignored. This monitoring system is essential for protecting the engine's internal components, particularly the crankshaft bearings and camshaft assembly.

Common Symptoms

• Engine warning light illuminated on the instrument panel, often amber or red depending on severity
• Engine power derate or automatic shutdown as a protective measure when oil pressure cannot be verified
• Erratic oil pressure gauge readings or gauge reading zero despite normal engine operation
• Audible warning alarm sounding in the operator cab alongside visual warnings
• Reduced hydraulic performance due to engine limiting torque output when fault is active

Potential Causes

The most common causes for Code 14103-2 on used ZX670LC-5A excavators include:

• Faulty oil pressure sensor due to internal sensor element failure or contamination from degraded engine oil
• Damaged sensor wiring harness, particularly at the routing point near the engine mount where vibration causes wire chafing
• Corroded or loose electrical connectors at the sensor plug, common in machines exposed to muddy or wet conditions
• Low engine oil level or use of incorrect viscosity oil creating actual low pressure conditions
• Short to ground in the sensor circuit wiring between the sensor and ECM
• ECM internal circuit failure (less common but possible in high-hour machines)

How to Troubleshoot and Fix Code 14103-2

Step 1: Visual Inspection and Oil Verification Check actual engine oil level using the dipstick and verify correct SAE 10W-30 oil is being used. Inspect the oil pressure sensor location on the engine block's left side and examine the three-pin connector for corrosion, oil contamination, or pushed-back pins.

Step 2: Sensor Circuit Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. A functional sensor should read 50-150 ohms at room temperature. Check for continuity to ground in the wiring harness—any reading below 10k ohms indicates a short circuit requiring harness repair.

Step 3: Voltage Signal Testing With the key on and engine off, backprobe the sensor connector and measure voltage. You should see approximately 5 volts reference voltage from the ECM. Start the engine and verify the signal voltage increases with RPM (typically 1.5-4.5 volts). If reference voltage is missing, suspect ECM power supply issues or internal ECM failure.

Step 4: Replacement and Verification For used excavators, physically inspect the wiring harness routing for wear points against the engine block or frame before replacing components. Replace the sensor with a genuine Hitachi part (4701163) and clear codes using Dr.EX diagnostic software or compatible scan tool. Run the engine through various load conditions to confirm repair.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Hitachi service manual for your specific machine serial number and consider professional assistance for complex electrical diagnostics or if unfamiliar with high-voltage systems.