What is Sany Excavator Fault Code P968?

Fault Code P968 indicates a malfunction in the hydraulic pump solenoid proportional valve circuit, specifically detecting an abnormal current or voltage signal that falls outside the Electronic Control Module's (ECM) expected parameters. This code triggers when the ECM detects either an open circuit, short circuit, or improper electrical response from the proportional valve that regulates hydraulic pump flow and pressure.

In Sany excavators, the hydraulic pump solenoid proportional valve is critical for controlling engine load matching and optimizing fuel efficiency while maintaining hydraulic performance. When this circuit malfunctions, the ECM cannot properly modulate pump displacement, leading to reduced machine performance and potential protection mode activation. This fault is particularly important in used machines where electrical connections and solenoid coils deteriorate over time due to heat cycling, vibration, and environmental exposure.

Common Symptoms

• Reduced hydraulic power across all functions (boom, arm, bucket, and swing operations feel sluggish)
• Engine warning light illuminated on the instrument cluster, possibly accompanied by a service reminder
• Automatic engine derate where the machine limits RPM to protect the hydraulic system
• Erratic hydraulic response with inconsistent flow rates during combined operations
• Increased fuel consumption as the system fails to optimize pump displacement relative to load demand

Potential Causes

The most common technical reasons for P968 appearing on used Sany excavators include:

• Damaged wiring harness at known rub points near the hydraulic pump mounting bracket where cable insulation wears through from vibration
• Failed proportional valve solenoid coil due to internal short circuits or open windings (resistance typically outside 8-15 ohm specification range)
• Corroded or loose connector pins at the solenoid valve plug, particularly on machines operating in wet or marine environments
• ECM internal driver circuit failure affecting the pulse-width modulation (PWM) signal output
• Contaminated hydraulic oil causing the proportional valve spool to stick, creating abnormal current draw
• Voltage supply issues from damaged power distribution harness or poor grounding connections

How to Troubleshoot and Fix Code P968

Step 1: Visual Inspection and Connector Check Begin by locating the hydraulic pump proportional valve solenoid mounted directly on the main pump assembly. Inspect the electrical connector for corrosion, bent pins, or oil contamination. On used excavators, pay special attention to the wiring harness routing where it passes near moving components or sharp metal edges—these are common failure points. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Electrical Testing with Multimeter Disconnect the solenoid connector and measure coil resistance across the solenoid terminals. Sany specifications typically require 10-13 ohms at room temperature. Next, check for supply voltage at the harness side connector with the ignition on—you should see battery voltage (12-14V). Test for short to ground by measuring resistance between each solenoid wire and chassis ground (should read infinite resistance/open circuit).

Step 3: Signal and Dynamic Testing Using Sany diagnostic software or a compatible scan tool, monitor the PWM duty cycle signal while operating the machine. The ECM should modulate the signal between 10-90% depending on load. If voltage and resistance readings are correct but the code persists, perform a solenoid activation test through the diagnostic software to verify mechanical operation. Listen for audible clicking from the valve.

Step 4: Component Replacement and System Verification If testing confirms solenoid failure, replace the proportional valve assembly with OEM or quality aftermarket parts. For used machines, always replace the connector pigtail simultaneously, as internal wire damage often exists even when external insulation appears intact. After replacement, clear fault codes, perform a hydraulic system calibration through diagnostic software, and cycle all hydraulic functions under load to verify proper operation.

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Disclaimer: This guide provides general troubleshooting information for Sany excavator fault code P968. Hydraulic and electrical system diagnostics require proper training and tools. Always consult the manufacturer's service manual for your specific model year and serial number, and consider engaging a certified Sany technician for complex repairs, especially on machines under warranty or service contracts.