Sumitomo SH350HD-6 Fault Code 606: Complete Diagnostic Guide

What is Sumitomo SH350HD-6 Fault Code 606?

Fault Code 606 on the Sumitomo SH350HD-6 indicates a hydraulic pump pressure sensor circuit malfunction or abnormal voltage reading. This code specifically relates to the main hydraulic pump's pressure transducer failing to communicate proper pressure data to the Electronic Control Module (ECM).

The SH350HD-6's advanced hydraulic management system relies on continuous pressure feedback to optimize pump output, prevent system overload, and protect critical components. When the ECM detects voltage readings outside the normal 0.5-4.5V range from the pressure sensor, it triggers Code 606 and may initiate protective measures. This is particularly critical on this model because the dual-pump system requires precise pressure monitoring to balance hydraulic flow between the attachment and swing circuits.

Common Symptoms

When Code 606 is active on your SH350HD-6, you may experience:

• Warning lamp illuminated on the instrument cluster with reduced hydraulic performance
• Sluggish or inconsistent boom/arm movements, particularly under heavy loads
• Intermittent loss of hydraulic power during operation, especially when multiple functions are used simultaneously
• Automatic engine derate to protect the hydraulic system from potential damage
• Erratic pressure gauge readings on the dashboard or complete gauge failure

Potential Causes

The most common technical causes for Code 606 on used SH350HD-6 excavators include:

• Pressure sensor failure due to internal diaphragm wear or electronic component degradation (common after 6,000+ hours)
• Damaged or corroded wiring harness at the sensor connector, particularly where the harness routes near the hydraulic tank and experiences vibration
• Contaminated electrical connections from hydraulic fluid leaks saturating the sensor connector
• ECM voltage supply issues providing incorrect reference voltage to the sensor circuit
• Worn sensor mounting threads causing poor grounding or vibration-induced intermittent connection
• Previous repair attempts using incorrect sensor specifications or aftermarket sensors with incompatible voltage ranges

How to Troubleshoot and Fix Code 606

Step 1: Visual Inspection Begin by locating the main pump pressure sensor mounted on the hydraulic pump assembly. Inspect the sensor connector and wiring harness for visible damage, corrosion, hydraulic fluid contamination, or abraded insulation. On used SH350HD-6 machines, check where the harness contacts the pump housing—this is a known wear point.

Step 2: Electrical Testing Disconnect the sensor and use a digital multimeter to check the ECM supply voltage at the harness connector (should read 5V ±0.25V with ignition on). Test sensor resistance across terminals (typically 250-350 ohms for OEM sensors). Check for continuity and short circuits to ground throughout the harness.

Step 3: Sensor Verification and Replacement If voltage supply is correct, reconnect the sensor and use Sumitomo diagnostic software to monitor live sensor output while operating the machine. Pressure readings should correlate with hydraulic demand. If readings are erratic or frozen, replace the pressure transducer with OEM-specification parts. Before installing the new sensor, clean mounting threads and apply dielectric grease to connector pins to prevent future corrosion.

Disclaimer: This guide provides general diagnostic information. Always consult the official Sumitomo SH350HD-6 service manual and consider professional assistance for complex hydraulic system repairs. Improper diagnosis can lead to costly component damage.