What is Hitachi ZX890LCH-5A Fault Code 14105-2?

Fault Code 14105-2 indicates a hydraulic oil temperature sensor circuit malfunction, specifically a low voltage or short-to-ground condition in the sensor circuit. This code is triggered when the Engine Control Module (ECM) detects voltage readings below the expected threshold from the hydraulic oil temperature sensor, which monitors the temperature of the hydraulic fluid circulating through the excavator's main hydraulic system.

This code is critical for the ZX890LCH-5A because the hydraulic oil temperature sensor plays a vital role in protecting the machine's hydraulic components from overheating damage. When this sensor fails or provides inaccurate readings, the ECM cannot properly manage hydraulic system performance, potentially leading to reduced efficiency, component wear, or catastrophic hydraulic system failure. The ZX890LCH-5A's advanced hydraulic system relies on precise temperature monitoring to optimize flow rates and prevent thermal breakdown of hydraulic fluid.

Common Symptoms

• Warning light illuminated on the instrument panel, specifically the hydraulic system caution indicator
• Erratic hydraulic oil temperature gauge readings or gauge stuck at minimum/cold reading regardless of actual operating temperature
• Reduced hydraulic performance or slower cycle times as the ECM may enter a protective derate mode
• Error message displayed on the multi-information display showing hydraulic system fault
• Intermittent loss of auxiliary hydraulic functions during operation as the system attempts to protect itself

Potential Causes

The most common causes of fault code 14105-2 on used ZX890LCH-5A excavators include:

• Damaged or corroded wiring harness near the hydraulic oil tank, where the sensor harness is exposed to hydraulic fluid mist and road debris
• Failed hydraulic oil temperature sensor due to age-related degradation or contamination from degraded hydraulic fluid
• Chafed or pinched sensor wiring at known rub points along the main frame rail near the hydraulic tank mounting brackets
• Corroded or loose connector pins at the sensor connection point or ECM harness connector
• Short-to-ground condition in the sensor circuit wiring, commonly occurring where harnesses pass through metal grommets
• ECM internal circuit failure (less common but possible in high-hour machines)

How to Troubleshoot and Fix Code 14105-2

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor on the hydraulic tank assembly. Inspect the sensor connector for corrosion, bent pins, or hydraulic oil contamination. Check the wiring harness from the sensor to the ECM for visible damage, chafing, or signs of previous repairs. On used excavators, pay special attention to areas where the harness contacts the frame or passes near rotating components.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. Compare readings against manufacturer specifications (typically 2,000-3,000 ohms at room temperature). Next, check for continuity between each sensor wire and ground—any continuity indicates a short-to-ground condition. Measure voltage supply at the sensor connector with the key on, engine off; you should see approximately 5 volts reference voltage from the ECM.

Step 3: Circuit and Component Testing If sensor readings are out of specification, replace the hydraulic oil temperature sensor with a genuine Hitachi part. If sensor tests good, inspect the entire wiring harness for hidden damage using a resistance test from the sensor connector back to the ECM pins. For used machines with high hours, consider replacing the entire sensor harness if multiple corrosion points are found. Clear the fault code using Hitachi Dr.EX diagnostic software or a compatible scan tool and perform a functional test.

Step 4: Verification After repairs, operate the machine through a complete warm-up cycle while monitoring hydraulic oil temperature readings on the display. Verify the gauge responds appropriately as the system reaches operating temperature (typically 40-80°C). Re-check for stored or active fault codes.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and seek assistance from certified Hitachi technicians for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.