What is Sany Excavator Fault Code P937?

Fault Code P937 indicates a malfunction in the hydraulic pump control system's pressure sensor circuit, specifically detecting an abnormal voltage signal or out-of-range pressure reading from the main pump pressure sensor. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) receives sensor data that falls outside predetermined voltage parameters, typically below 0.5V or above 4.5V on a standard 5V reference circuit.

This code is critical for Sany excavators because the main pump pressure sensor directly influences hydraulic flow compensation and load-sensing functions. When the ECM cannot accurately read hydraulic pressure, it defaults to a protective mode that significantly limits machine performance, preventing potential damage to expensive hydraulic components but severely impacting productivity on job sites.

Common Symptoms

• Hydraulic power loss or noticeably reduced digging force and swing speed, even at full throttle
• Amber warning light illuminated on the instrument cluster, often accompanied by a wrench or hydraulic system icon
• Engine derating where RPMs are automatically limited to 1,500-1,800 range regardless of throttle input
• Erratic or sluggish boom, arm, and bucket response with inconsistent cycle times
• Diagnostic display showing P937 code when scanned with compatible service tools

Potential Causes

The most common technical failures triggering P937 on used Sany excavators include:

• Pressure sensor failure due to internal diaphragm rupture or electronic component degradation (common after 4,000+ operating hours)
• Wiring harness damage at the sensor connector or along the routing path near the hydraulic pump, where vibration and heat cause insulation breakdown
• Corroded or oil-contaminated connector pins at the sensor interface, creating high resistance
• ECM voltage supply issues where the 5V reference circuit develops faults
• Physical damage to sensor mounting threads causing hydraulic fluid leaks and sensor contamination
• Intermittent short circuits in harness sections routed near sharp metal edges (known issue on 2015-2018 models)

How to Troubleshoot and Fix Code P937

Step 1: Visual Inspection Begin with the pressure sensor located on the main hydraulic pump body. Inspect the electrical connector for oil contamination, bent pins, or corrosion—common on used machines operating in wet conditions. Check the wiring harness for abrasion points where it contacts the pump housing or frame rails.

Step 2: Electrical Testing Using a digital multimeter, backprobe the sensor connector with the ignition on (engine off). Verify the 5V reference voltage on the supply wire and confirm ground continuity (less than 0.5 ohms resistance). With the sensor connected, the signal wire should read between 0.8V-4.2V at atmospheric pressure. Readings outside this range indicate sensor failure.

Step 3: Sensor Replacement and Harness Verification If voltage tests confirm sensor failure, replace with an OEM Sany pressure sensor (part number typically SY-series specific). Before installation, apply dielectric grease to connector pins. For used excavators, carefully inspect harness routing and secure any sections with excessive wear using protective loom and proper standoffs. Clear codes with diagnostic software and perform a hydraulic system test cycle.

Critical for Used Equipment: Always check for previous repair attempts, aftermarket sensors, or jury-rigged wiring that may mask underlying harness damage.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Sany service manual for your specific model and serial number. Complex hydraulic-electrical issues may require certified technician diagnosis with factory-level diagnostic equipment.