What is Sany Excavator Fault Code P845?

Fault Code P845 indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically detecting an abnormal electrical signal or open/short circuit condition in the pump control system. This diagnostic trouble code (DTC) is generated when the Electronic Control Module (ECM) detects voltage or current values outside the manufacturer's specified parameters for the hydraulic pump's proportional solenoid valve.

For Sany excavators, this code is critical because the hydraulic pump solenoid directly regulates pump displacement and flow rate, which controls the machine's overall hydraulic performance. When P845 activates, the ECM typically enters a limp mode or derate condition to protect the hydraulic system from potential damage, significantly limiting operational capability.

Common Symptoms

• Reduced hydraulic power across all functions (boom, arm, bucket, swing) with noticeably slower cycle times
• Amber or red warning light illuminated on the instrument cluster, often accompanied by an audible alarm
• Erratic hydraulic response where functions may work intermittently or respond unpredictably to joystick inputs
• Engine RPM fluctuation during hydraulic operations as the ECM attempts to compensate for pump control issues
• Complete loss of hydraulic function in severe cases where the ECM disables pump operation entirely

Potential Causes

• Damaged wiring harness between the ECM and hydraulic pump solenoid, particularly at flex points near the pump mounting area where vibration causes wire chafing
• Failed proportional solenoid valve due to internal coil breakdown, contamination, or mechanical wear common in high-hour used machines
• Corroded or loose electrical connectors at the pump solenoid or ECM interface, especially on machines operated in wet or corrosive environments
• ECM internal fault or software corruption affecting the solenoid driver circuit
• Voltage supply issues from the main power harness, including poor grounds or battery connection problems

How to Troubleshoot and Fix Code P845

Step 1: Visual Inspection Begin by thoroughly inspecting the wiring harness from the ECM to the hydraulic pump solenoid valve. On used excavators, check for worn insulation, pinched wires at cable ties, or harness damage where it routes along the pump. Examine all connector pins for corrosion, bent terminals, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure coil resistance (typically 8-15 ohms for Sany applications—verify with service manual). Test for continuity in the harness between the solenoid and ECM connector. Check supply voltage at the solenoid connector with ignition on (should read 12-24V depending on system specifications).

Step 3: Solenoid and ECM Verification If wiring tests pass, swap the solenoid valve with a known good component or new OEM part. Clear codes using Sany diagnostic software and test operation. If P845 persists after solenoid replacement with confirmed good wiring, the ECM solenoid driver circuit may require professional repair or ECM replacement.

Critical Note for Used Machines: Before replacing expensive components, thoroughly clean all electrical connections with contact cleaner and apply dielectric grease. Check engine and chassis ground connections, as poor grounds frequently cause intermittent electrical faults in aging equipment.

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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. Complex electrical diagnostics should be performed by qualified technicians with appropriate diagnostic tools.