What is Sany General Fault Code P806?

Fault Code P806 on Sany excavators indicates a Hydraulic Pump Solenoid Circuit Malfunction, specifically detecting an abnormal electrical signal in the main pump control solenoid valve circuit. This diagnostic trouble code (DTC) is generated when the Electronic Control Module (ECM) detects a voltage irregularity, open circuit, short circuit, or improper resistance in the wiring or solenoid that controls hydraulic pump displacement.

This code is critical for Sany excavators because the hydraulic pump solenoid directly regulates flow and pressure, controlling all machine functions from boom operation to swing speed. When P806 triggers, the ECM may command the excavator into a derate mode or default to minimum pump output to prevent component damage, severely limiting productivity on jobsites.

Common Symptoms

• Reduced hydraulic power across all functions, with slow or sluggish boom, arm, and bucket movements
• Illuminated warning light on the instrument panel, often accompanied by a wrench or engine symbol
• Inconsistent swing speed or jerky hydraulic response during combined operations
• Error message displayed on the monitor screen showing "P806" or "Hydraulic System Fault"
• Machine may enter limp mode, restricting engine RPM to 1200-1500 range to protect the hydraulic system

Potential Causes

The following technical issues commonly trigger P806 on used Sany excavators:

• Faulty hydraulic pump solenoid valve due to internal coil failure or mechanical sticking from contamination
• Damaged wiring harness near the main pump assembly, especially at known rub points where the harness contacts the frame during boom articulation
• Corroded or loose electrical connectors at the solenoid valve, particularly on machines with 3,000+ operating hours
• ECM internal fault or software corruption requiring reprogramming
• Voltage supply issues from a failing alternator or weak battery causing inadequate power to the solenoid circuit
• Hydraulic fluid contamination causing the solenoid spool to bind, increasing electrical draw and triggering fault detection

How to Troubleshoot and Fix Code P806

Step 1: Initial Inspection and Code Verification Connect a diagnostic laptop with Sany-compatible software (SY Explorer or equivalent) to confirm P806 is active and check for additional stored codes. Record freeze frame data showing conditions when the fault occurred. Visually inspect the hydraulic pump solenoid connector for oil contamination, bent pins, or corrosion—common issues on used excavators operating in wet environments.

Step 2: Electrical Circuit Testing Disconnect the solenoid connector and use a digital multimeter to measure resistance across the solenoid terminals. Typical specification is 8-15 ohms (consult your service manual for exact values). Test supply voltage at the harness connector with the ignition on—should read 12-14 volts DC. Check for continuity between the solenoid ground and chassis ground, ensuring less than 0.5 ohms resistance.

Step 3: Harness and Connector Inspection On used machines, carefully trace the wiring harness from the ECM to the pump solenoid, inspecting for abrasion points where cables contact metal edges near the pump mounting bracket. Check for heat damage or melted insulation near the engine block. Clean all connectors with electrical contact cleaner and apply dielectric grease to prevent future corrosion.

Step 4: Solenoid Replacement or Repair If resistance or voltage tests fail specifications, replace the hydraulic pump solenoid valve. Before installation, flush the area around the pump with clean hydraulic fluid to remove metal particles. After replacement, clear codes using diagnostic software and perform a solenoid output test to verify proper ECM command signals (typically PWM signals at 200-500 Hz).

Step 5: System Verification Cycle the excavator through all hydraulic functions while monitoring live data. Verify the ECM shows proper solenoid current draw (usually 0.8-1.5 amps) and that P806 does not return. Check hydraulic system pressure with a test gauge to confirm it meets specification (typically 320-350 bar at rated RPM).

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Disclaimer: This guide provides general troubleshooting information for Sany excavator fault code P806. Hydraulic and electrical systems operate under high pressure and voltage. Always consult the manufacturer's service manual for your specific model and serial number, and consider professional diagnostic assistance if you lack specialized tools or experience with heavy equipment repair.