What is Hitachi ZX350K-5G Fault Code 11301-3?

Fault Code 11301-3 on the Hitachi ZX350K-5G excavator indicates a communication error or abnormal signal from the hydraulic pump discharge pressure sensor circuit. This code is generated when the Electronic Control Module (ECM) detects an out-of-range voltage signal, intermittent connection, or sensor malfunction within the main hydraulic system's pressure monitoring circuit.

This specific fault is critical because the discharge pressure sensor provides real-time data to the ECM for optimizing pump output, preventing system overload, and protecting hydraulic components from damage. On the ZX350K-5G model, this sensor directly influences the pump flow control system, and any malfunction can lead to inefficient operation, reduced digging force, or complete system shutdown to prevent catastrophic failure.

Common Symptoms

When fault code 11301-3 is active, operators typically experience:

• Hydraulic system warning light illuminated on the instrument cluster
• Reduced hydraulic power or sluggish response during boom, arm, or bucket operations
• Intermittent loss of hydraulic function, particularly under heavy load conditions
• Error messages displayed on the monitor panel indicating pressure sensor issues
• Engine derate mode engagement in severe cases, limiting RPM to protect the system

Potential Causes

The most common technical reasons for this fault code on used ZX350K-5G excavators include:

• Faulty hydraulic pump discharge pressure sensor due to internal component wear or contamination
• Damaged or corroded wiring harness connections at the sensor plug (common wear point near the main pump)
• Broken or chafed sensor wiring caused by vibration or contact with hydraulic lines
• ECM internal fault or corrupted calibration data affecting sensor signal interpretation
• Contaminated hydraulic oil causing sensor tip fouling or membrane damage
• Poor ground connection at the sensor mounting point or ECM harness ground

How to Troubleshoot and Fix Code 11301-3

Step 1: Visual Inspection Begin by inspecting the pressure sensor located on the main hydraulic pump assembly. Check for physical damage, oil leaks around the sensor body, and examine the wiring harness for signs of chafing, corrosion, or connector damage. On used excavators, pay special attention to harness routing near moving components where friction wear commonly occurs.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals (typically 50-150 ohms depending on temperature). Check supply voltage at the harness connector (should read approximately 5 volts with ignition on). Test signal wire continuity from sensor to ECM and verify proper ground circuit resistance (less than 5 ohms).

Step 3: Sensor Output Verification With the engine running, use Hitachi diagnostic software (Dr.EX) to monitor live sensor data. Compare actual pressure readings against expected values during idle and loaded conditions. If readings are erratic or frozen, replace the pressure sensor after cleaning the mounting threads and applying anti-seize compound.

Step 4: Harness and Connector Repair Inspect all connector pins for corrosion or bent terminals. On older machines, connector seal degradation allows moisture intrusion—clean with electrical contact cleaner and apply dielectric grease before reconnection. Repair any damaged wiring using proper gauge wire and heat-shrink connections.

Disclaimer: This guide provides general troubleshooting procedures. Always consult the official Hitachi service manual for your specific serial number and seek professional assistance from certified technicians for complex electrical diagnostics or hydraulic system repairs.