What is Sany Excavator Fault Code H087?

Fault Code H087 on Sany excavators indicates a malfunction in the hydraulic oil temperature sensor circuit or an abnormal hydraulic oil temperature reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects that the hydraulic oil temperature sensor signal is out of the normal operating range, either too high, too low, or indicating a circuit fault (open or short).

This code is critical for Sany excavators because the hydraulic system relies on optimal oil temperature for proper viscosity and component protection. When hydraulic oil becomes too hot, it loses lubrication properties and can damage pumps, motors, and valves. Conversely, if the temperature sensor provides false readings, the ECM cannot protect the system from thermal damage or adjust performance parameters accordingly.

Common Symptoms

When fault code H087 is active, operators typically experience:

• Warning light illuminated on the instrument cluster, often accompanied by a hydraulic system alert
• Reduced hydraulic system performance or derate mode activation to protect components
• Erratic hydraulic response or sluggish movement of boom, arm, or bucket functions
• Audible warning alarm from the cab indicating a hydraulic system fault
• Inaccurate temperature gauge readings on the display panel, showing unusually high or low values

Potential Causes

The most common technical reasons for H087 in used Sany excavators include:

• Failed or degraded hydraulic oil temperature sensor due to age and thermal cycling
• Damaged or corroded wiring harness connections at the sensor plug, especially near high-vibration areas
• Chafed or pinched sensor wires where the harness routes along the hydraulic tank or frame rails
• Contaminated hydraulic oil causing sensor probe fouling or coating
• ECM internal fault or corrupted software calibration (less common)
• Actual hydraulic oil overheating due to cooler blockage, making the sensor reading legitimate

How to Troubleshoot and Fix Code H087

Step 1: Visual Inspection Begin by locating the hydraulic oil temperature sensor, typically mounted on the hydraulic tank. Inspect the sensor body and connector for physical damage, corrosion, oil contamination, or loose pins. On used excavators, check for harness wear at known rub points along the tank mounting brackets.

Step 2: Electrical Testing Disconnect the sensor connector and use a multimeter to measure resistance across the sensor terminals. Compare readings against Sany specifications (typically 2,000-3,000 ohms at room temperature for NTC sensors). Check for continuity in the wiring harness from sensor to ECM, and test for shorts to ground.

Step 3: Sensor Replacement and Verification If the sensor tests out of specification or the harness shows damage, replace the faulty component. Use genuine Sany parts to ensure proper voltage output and ECM compatibility. Clear the fault code using Sany diagnostic software or a compatible scan tool, then operate the machine through normal temperature cycles to verify the repair.

For used machines, always inspect hydraulic oil condition and cooler function, as legitimate overheating can trigger this code repeatedly even after sensor replacement.

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Disclaimer: This guide provides general troubleshooting information. Always consult factory service manuals and qualified technicians for your specific Sany model before performing repairs.