Sumitomo SH300-6 Fault Code 602: Complete Diagnostic Guide

What is Sumitomo SH300-6 Fault Code 602?

Fault Code 602 on the Sumitomo SH300-6 excavator indicates a malfunction in the engine oil pressure sensor circuit or abnormally low engine oil pressure detection. This code is triggered when the Electronic Control Module (ECM) receives signals outside the expected voltage range from the oil pressure sensor, or when actual oil pressure falls below the manufacturer's minimum threshold during operation.

This fault is critical for the SH300-6 because inadequate oil pressure monitoring can lead to catastrophic engine damage. The Isuzu diesel engine in this model relies on precise oil pressure feedback to protect critical components like crankshaft bearings, camshaft lobes, and turbocharger assemblies. When Code 602 activates, the ECM may initiate protective measures including power derate or automatic shutdown.

Common Symptoms

When Code 602 is active on your SH300-6, operators typically experience:

• Oil pressure warning light illuminated on the instrument cluster (red oil can symbol)
• Engine power reduction or derate mode, limiting maximum RPM to approximately 1,200-1,500
• Audible alarm sounding continuously in the operator cab
• Rough idling or hesitation during throttle application
• In severe cases, automatic engine shutdown after a brief warning period (typically 30-60 seconds)

Potential Causes

The most common technical reasons for Code 602 on used SH300-6 excavators include:

• Failed oil pressure sensor (common failure point after 5,000+ operating hours)
• Damaged or corroded wiring harness connections at the sensor—particularly where the harness routes near the engine block and experiences heat cycling
• Low actual engine oil pressure due to worn oil pump, clogged oil filter, or incorrect oil viscosity
• ECM internal fault or corrupted calibration data (less common)
• Blocked oil passages or excessive bearing clearances in high-hour machines
• Intermittent short circuits caused by chafed wires against frame rails or engine mounts

How to Troubleshoot and Fix Code 602

Step 1: Visual Inspection Begin by inspecting the oil pressure sensor located on the engine block's left side (typically near the oil filter housing). Check the connector for corrosion, bent pins, or oil contamination. On used excavators, examine the entire wiring harness for rub-through points where it contacts metal surfaces—this is a known wear area on SH300-6 models.

Step 2: Verify Actual Oil Pressure Install a mechanical oil pressure gauge at the sensor port. Start the engine and compare readings against Sumitomo specifications (typically 30-50 PSI at idle, 50-70 PSI at high idle). If mechanical pressure is adequate but the code persists, the issue is electrical.

Step 3: Electrical Testing Using a digital multimeter, check the sensor's resistance (typically 50-150 ohms depending on temperature) and output voltage (0.5-4.5V range). Test harness continuity from sensor to ECM pin and check for shorts to ground. Corroded connectors are especially common in machines operating in wet or marine environments.

Step 4: Component Replacement Replace the oil pressure sensor first if electrical values are out of range—this resolves 70% of Code 602 cases on used machines. If the problem persists, inspect the oil pump and internal engine components, as this may indicate mechanical wear requiring professional overhaul.

---

Disclaimer: This guide provides general diagnostic information. Always consult the Sumitomo SH300-6 service manual and consider professional evaluation for complex engine issues, especially on high-hour used equipment where multiple systems may require attention.