What is Sany Excavator Fault Code P105?

Fault Code P105 on Sany excavators indicates a malfunction in the hydraulic pump pressure sensor circuit or an abnormal pressure reading detected by the Engine Control Module (ECM). This code specifically relates to the main hydraulic pump's pressure monitoring system, which is critical for maintaining optimal hydraulic performance and protecting the machine from potential damage.

The hydraulic pump pressure sensor continuously monitors system pressure and sends voltage signals to the ECM. When the ECM detects voltage readings outside the manufacturer's specified range (typically 0.5-4.5V), or when actual pressure deviates significantly from expected values during operation, it triggers P105. This fault is particularly critical for Sany excavators because the hydraulic system directly affects digging force, swing speed, and overall operational efficiency. Ignoring this code can lead to reduced performance, component overheating, or catastrophic pump failure.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Intermittent or constant warning light on the instrument cluster, often accompanied by an audible alarm
• Engine derating or automatic RPM reduction to protect the hydraulic system from damage
• Erratic hydraulic response, where attachments move inconsistently or hesitate during operation
• Error messages displayed on the monitor indicating hydraulic system faults or pressure anomalies

Potential Causes

The most common causes of P105 in used Sany excavators include:

• Faulty hydraulic pump pressure sensor due to internal component wear or contamination from hydraulic fluid debris
• Damaged wiring harness or corroded connectors, particularly at rub points near the pump mounting area or along the main chassis harness
• Poor electrical connections at the sensor connector caused by moisture intrusion, oil contamination, or loose pins
• Actual hydraulic system pressure problems, including worn pump components, stuck relief valves, or contaminated hydraulic oil
• ECM software issues or corrupted calibration data (less common but possible in older machines)
• Voltage supply problems from the machine's electrical system affecting sensor power delivery

How to Troubleshoot and Fix Code P105

Step 1: Visual Inspection Begin with a thorough inspection of the hydraulic pump pressure sensor and its wiring. Located near the main hydraulic pump, check for physical damage, oil leaks, or loose connections. On used excavators, pay special attention to harness wear points where cables contact metal frames or moving components. Clean any corroded connectors with electrical contact cleaner.

Step 2: Electrical Testing Using a digital multimeter, check the sensor's power supply (should be approximately 5V) and ground continuity at the connector. Measure the sensor's output voltage while the engine is running—it should vary smoothly with hydraulic demand (typically 0.5-4.5V). Compare readings against Sany's specifications using diagnostic software like Sany PC-E or compatible tools. Check wiring resistance between the sensor and ECM (should be under 5 ohms).

Step 3: Sensor and System Verification If electrical values are correct, install a mechanical pressure gauge directly into the hydraulic system to verify actual pressure readings. Compare mechanical gauge readings with sensor output—discrepancies indicate sensor failure. Test hydraulic oil condition; contaminated fluid can damage sensors. For used machines, consider that sensor drift is common after 5,000+ operating hours.

Step 4: Component Replacement and Calibration Replace the pressure sensor if testing confirms failure (genuine Sany parts recommended for proper ECM communication). After replacement, clear fault codes and perform system calibration using diagnostic software. Monitor the machine during operation to ensure the code doesn't return.

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Disclaimer: This guide provides general troubleshooting information. Hydraulic systems operate under extreme pressure and require proper training. Always consult Sany service manuals and consider professional diagnostic assistance for complex issues, especially on used equipment with unknown service history.