What is Sany Excavator Fault Code P350?

Fault Code P350 indicates a malfunction in the hydraulic pump pressure sensor circuit or abnormal pressure readings detected by the Engine Control Module (ECM). This diagnostic trouble code specifically relates to the main hydraulic pump's pressure monitoring system, which is critical for regulating hydraulic flow and preventing catastrophic pump damage on Sany excavators.

The hydraulic pump pressure sensor continuously sends voltage signals to the ECM, allowing the system to adjust pump output based on operational demands. When the ECM detects voltage readings outside the normal range (typically 0.5-4.5 volts) or pressure values that don't correlate with actual system load, Code P350 is triggered. This fault is particularly critical because the hydraulic system is the lifeblood of excavator operation—controlling everything from boom movement to track drive. Ignoring this code can lead to reduced hydraulic performance, component overheating, or complete pump failure.

Common Symptoms

• Dashboard warning light illuminated (typically a hydraulic system or engine malfunction indicator)
• Reduced hydraulic power across all functions—slow boom, arm, or bucket movements
• Erratic hydraulic response where implements move inconsistently or surge unexpectedly
• Engine derate mode activated, limiting RPM to protect the hydraulic system
• Abnormal pump noise such as whining or cavitation sounds under load

Potential Causes

On used Sany excavators, Code P350 typically stems from age-related component degradation:

• Failed hydraulic pump pressure sensor—internal element failure common after 5,000+ operating hours
• Damaged wiring harness near the main pump area where vibration and heat cause insulation breakdown
• Corroded or loose electrical connectors at the sensor or ECM interface
• ECM calibration drift or software corruption (less common but possible in older machines)
• Actual hydraulic pressure problems—worn pump components causing genuine low pressure conditions
• Contaminated hydraulic oil affecting sensor accuracy through particulate interference

How to Troubleshoot and Fix Code P350

Step 1: Visual Inspection Begin by inspecting the hydraulic pump pressure sensor (located on the main pump housing) and its wiring harness. On used excavators, check for oil contamination on connectors, physical damage to wiring from rubbing against the pump casing, and connector pin corrosion. Clean all connections with electrical contact cleaner.

Step 2: Electrical Testing Using a digital multimeter, check the sensor's supply voltage (should be 5V ±0.25V with key on, engine off). Then measure sensor signal voltage at idle and under load—readings should range from approximately 0.8V (low pressure) to 4.2V (high pressure). Resistance checks across sensor terminals should match manufacturer specifications (typically 250-350 ohms).

Step 3: Sensor Replacement and Verification If voltage readings are erratic or out of range, replace the pressure sensor with a genuine Sany part. Before installation, inspect the sensor mounting port for metal debris or damaged threads—common in used machines. After replacement, clear the fault code using Sany diagnostic software and perform a hydraulic system function test under various loads.

Step 4: Hydraulic System Assessment If the code persists after sensor replacement, measure actual hydraulic pressure using a test gauge at the pump outlet. Compare readings to specifications (typically 320-350 bar at relief). Low pressure indicates internal pump wear requiring rebuild or replacement.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sany service manual for your specific model and consider professional diagnostic assistance for complex electrical or hydraulic issues.