Sumitomo SH260LC-6 Fault Code 118: Complete Diagnostic Guide

What is Sumitomo SH260LC-6 Fault Code 118?

Fault Code 118 on the Sumitomo SH260LC-6 excavator indicates a malfunction in the Engine Oil Pressure Sensor Circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage signal from the oil pressure sensor, typically indicating an open circuit, short circuit, or sensor failure.

The oil pressure monitoring system is critical for the Isuzu engine powering this excavator model. The ECM continuously monitors oil pressure to prevent catastrophic engine damage from inadequate lubrication. When Code 118 activates, the machine's protective systems may limit performance to safeguard internal engine components from potential seizure or bearing failure.

Common Symptoms

Operators experiencing Code 118 may notice:

• Engine warning light illuminated on the instrument cluster with reduced power output
• Automatic engine derate limiting RPM to protect against low oil pressure damage
• Erratic or zero oil pressure gauge readings despite normal engine operation
• Intermittent engine shutdown in severe cases, particularly during high-load conditions
• Audible alarm sounding from the cab when code becomes active

Potential Causes

In used Sumitomo SH260LC-6 excavators, Code 118 typically results from:

• Failed oil pressure sensor due to age-related internal diaphragm deterioration or contamination
• Damaged or corroded wiring harness between the sensor and ECM, especially near engine vibration points
• Loose or oxidized electrical connectors at the sensor or ECM interface
• Short to ground in sensor signal wire caused by harness rubbing against engine block or frame
• Low engine oil level triggering genuine low pressure and sensor activation
• Faulty ECM (rare, but possible in high-hour machines with moisture exposure)

How to Troubleshoot and Fix Code 118

Step 1: Visual Inspection Check actual engine oil level using the dipstick. Inspect the oil pressure sensor (located on the engine block near the oil filter) for physical damage, oil leaks, or loose mounting. Examine the wiring harness for abrasion, cuts, or signs of rubbing against hot or moving components—common on used machines with 5,000+ hours.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to check sensor resistance (typically 50-150 ohms when cold; consult service manual for exact specifications). Test signal wire voltage at the ECM connector with ignition on—should read approximately 5 volts reference voltage. Check for continuity and shorts to ground in the harness.

Step 3: Component Replacement If sensor readings are out of specification or harness shows damage, replace the defective component. For used excavators, always apply dielectric grease to connector pins to prevent future corrosion. Clear codes using Sumitomo diagnostic software or compatible scan tool, then perform a test run under load.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual and consider professional diagnostic assistance for complex electrical issues or if unfamiliar with high-pressure hydraulic systems.