What is Hitachi ZX170W-3 Fault Code 11920-2?

Fault Code 11920-2 indicates a hydraulic pressure sensor circuit malfunction in the main hydraulic pump system of the Hitachi ZX170W-3 wheeled excavator. This diagnostic trouble code (DTC) specifically signals that the Electronic Control Module (ECM) has detected an abnormal voltage reading from the main pump pressure sensor, typically registering values outside the normal 0.5-4.5 volt operating range.

This code is critical for the ZX170W-3 because the hydraulic pressure sensor provides real-time feedback to the machine's load-sensing hydraulic system. When this sensor fails or provides inaccurate readings, the ECM cannot properly regulate pump output, leading to reduced operational efficiency, potential component damage, and compromised safety during operation.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Intermittent or continuous warning indicator on the instrument cluster display panel
• Erratic engine RPM fluctuations when operating under load due to improper pump control
• Unusual hydraulic system noise or cavitation sounds from the main pump assembly
• Machine entering derate mode, limiting engine output to protect hydraulic components

Potential Causes

The most common causes of Code 11920-2 in used Hitachi ZX170W-3 excavators include:

• Failed hydraulic pressure sensor due to internal diaphragm rupture or electrical component degradation
• Damaged wiring harness at known wear points near the main pump mounting bracket where vibration causes insulation breakdown
• Corroded or loose connector pins at the sensor connection point, especially in machines exposed to moisture or operated in marine environments
• ECM power supply issues affecting the 5-volt reference voltage supplied to the sensor circuit
• Contaminated hydraulic oil causing sensor membrane fouling or internal blockage

How to Troubleshoot and Fix Code 11920-2

Step 1: Visual Inspection and Connection Check Begin by accessing the main hydraulic pump pressure sensor located on the pump housing. Disconnect the sensor 3-pin connector and inspect for corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner and apply dielectric grease upon reassembly.

Step 2: Electrical Circuit Testing Using a digital multimeter, check for 5-volt reference voltage at the sensor harness connector with ignition on, engine off. Measure sensor output voltage while manually observing pressure gauge readings during engine operation. Values outside 0.5-4.5 volts indicate sensor replacement is required.

Step 3: Harness and Ground Verification Trace the sensor wiring harness from the pump to the ECM, paying special attention to routing near the pump drive shaft and engine mounting points where used excavators commonly develop harness chafing. Test ground circuit continuity (should read less than 1 ohm resistance).

Step 4: Sensor Replacement and System Reset If testing confirms sensor failure, install a genuine Hitachi pressure sensor (Part No. 4448336 or equivalent). After installation, clear fault codes using Hitachi Dr.EX diagnostic software or compatible J1939 scan tool. Perform a test cycle under load to verify repair.

For used excavators, always inspect hydraulic oil condition and consider changing filters, as contamination accelerates sensor failure.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the official Hitachi ZX170W-3 service manual and consider professional technician assistance for complex hydraulic system repairs.