Hitachi ZX870-5A (HCMC) Fault Code 20113-2: Complete Diagnostic Guide

What is Hitachi ZX870-5A Fault Code 20113-2?

Fault Code 20113-2 indicates a malfunction in the hydraulic oil temperature sensor circuit, specifically detecting an abnormal voltage signal or open circuit condition in the hydraulic system temperature monitoring.

This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) receives voltage readings outside the normal operating range from the hydraulic oil temperature sensor. For the ZX870-5A excavator, accurate hydraulic temperature monitoring is critical for protecting the system from thermal damage and maintaining optimal viscosity for component longevity. When this sensor fails, the machine cannot properly regulate hydraulic system performance, potentially leading to accelerated wear or catastrophic hydraulic pump failure.

Common Symptoms

When fault code 20113-2 is active, operators typically experience:

• Warning light illumination on the instrument cluster, specifically the hydraulic system alert indicator
• Reduced hydraulic performance or automatic derate mode, limiting machine speed and power output
• Inaccurate temperature gauge readings showing unrealistic values (extremely high, low, or frozen readings)
• Intermittent fault activation, especially during cold starts or when operating in extreme temperatures
• ECM logging multiple instances of the fault without corresponding physical temperature issues

Potential Causes

The most common technical failures triggering this code on used ZX870-5A excavators include:

• Damaged or corroded sensor connector pins at the hydraulic tank mounting location, exposed to moisture and contaminants
• Sensor element failure due to prolonged exposure to thermal cycling and hydraulic fluid degradation
• Wiring harness chafing at known rub points near the hydraulic tank and along the main chassis routing path
• ECM internal circuit degradation, particularly in high-hour machines with previous electrical system issues
• Poor ground connections at the sensor mounting point or ECM ground terminals
• Hydraulic fluid contamination causing sensor element coating and resistance changes

How to Troubleshoot and Fix Code 20113-2

Step 1: Visual Inspection and Connector Verification

Begin by locating the hydraulic oil temperature sensor mounted on the hydraulic tank. Disconnect the electrical connector and inspect for corrosion, bent pins, moisture intrusion, or oil contamination. On used excavators, this connection point frequently suffers from environmental exposure. Clean connectors with electrical contact cleaner and examine the wiring harness for visible damage or wear marks.

Step 2: Sensor Resistance Testing

Using a digital multimeter (DMM), measure the sensor resistance at various temperatures. Consult the Hitachi service manual for specific resistance values, but typical NTC (Negative Temperature Coefficient) sensors should show approximately 2,000-3,000 ohms at 20°C (68°F). Compare readings against manufacturer specifications. If resistance is infinite (open circuit) or near zero (short circuit), sensor replacement is required.

Step 3: Wiring Harness and Voltage Supply Check

With the connector disconnected, measure supply voltage from the ECM at the harness side—typically 5 volts reference. Check for continuity between the sensor signal wire and ECM pin using wiring diagrams. Pay special attention to harness routing near hydraulic lines and structural members where abrasion damage commonly occurs on high-hour machines. Repair or replace damaged sections using proper gauge wire and environmental protection.

Step 4: ECM Signal Verification

Using Hitachi Dr.EX diagnostic software or compatible diagnostic tools, monitor live sensor data while applying controlled temperature changes (heat gun on LOW setting). The signal should change smoothly without dropouts. Erratic readings indicate intermittent wiring faults. Clear codes and perform a functional test under operating conditions.

Critical Note for Used Equipment: Before replacing components, thoroughly inspect all harness securing clips, grommets, and protective sleeving. Older excavators frequently develop issues from deteriorated wire protection rather than component failure itself.

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Disclaimer: This guide provides general diagnostic procedures for informational purposes. Always consult the official Hitachi service manual for your specific machine serial number and software version. Complex electrical diagnostics should be performed by qualified technicians with proper training and equipment. Improper repairs may void warranties or create safety hazards.