Sany Excavator Fault Code 44: Complete Diagnostic Guide

What is Sany Excavator Fault Code 44?

Fault Code 44 on Sany excavators indicates a malfunction in the hydraulic oil temperature sensor circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage reading from the hydraulic oil temperature sensor, typically caused by an open circuit, short circuit, or sensor failure.

This code is critical because the hydraulic system relies on accurate temperature monitoring to prevent overheating and maintain optimal viscosity. When the ECM cannot read hydraulic oil temperature correctly, it may activate protection modes that limit machine performance or trigger unnecessary safety shutdowns, directly impacting productivity on the job site.

Common Symptoms

When Fault Code 44 is active, operators typically experience:

• Warning light illuminated on the instrument panel, often accompanied by a specific fault code display
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions
• Reduced hydraulic performance as the system enters derate mode to protect components
• Intermittent loss of power during operation, especially during high-demand tasks
• Cooling fan running continuously at high speed, even when hydraulic oil is not hot

Potential Causes

The most common technical causes for Code 44 on used Sany excavators include:

• Faulty hydraulic oil temperature sensor due to age-related degradation or contamination exposure
• Damaged wiring harness at known rub points near the hydraulic tank, pump mounting area, or chassis frame
• Corroded or loose connector pins at the sensor plug, especially common in machines operating in wet or marine environments
• Broken or chafed wires where the harness passes through grommets or metal brackets
• ECM internal fault (rare, but possible in older machines with high operating hours)
• Poor ground connection at the sensor mounting point or main chassis ground

How to Troubleshoot and Fix Code 44

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor, typically mounted on the hydraulic tank or main pump housing. Inspect the entire wiring harness from sensor to ECM for visible damage, chafing, or oil contamination. On used excavators, pay special attention to areas where the harness contacts metal edges or moving components.

Step 2: Connector and Resistance Testing Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture. Using a digital multimeter, measure sensor resistance—typical values range from 2,000-3,000 ohms at room temperature (refer to Sany service manual for exact specifications). Compare readings against a temperature-resistance chart.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition on, measure voltage at the ECM side of the connector. You should see approximately 5 volts reference voltage. If voltage is absent, trace the wire back to the ECM for breaks or shorts to ground.

Step 4: Sensor Replacement and Verification If the sensor fails resistance testing or the harness shows damage, replace the defective component with OEM or quality aftermarket parts. After replacement, clear codes using Sany diagnostic software or a compatible scanner, then operate the machine through a full temperature cycle to verify repair.

For used excavators: Before replacing expensive components, thoroughly clean all connectors with electrical contact cleaner and apply dielectric grease. Many Code 44 occurrences on older machines are resolved simply by addressing corroded connections.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Sany service manual for your specific model and serial number. If you're uncomfortable performing electrical diagnostics, contact a certified Sany technician or qualified heavy equipment mechanic.