Sumitomo SH220LC-5 Fault Code 1095: Complete Diagnostic Guide

What is Sumitomo SH220LC-5 Fault Code 1095?

Fault Code 1095 on the Sumitomo SH220LC-5 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM). This code typically triggers when the ECM receives a voltage signal outside the expected range from the coolant temperature sensor, suggesting either a sensor failure, wiring issue, or actual overheating condition.

The coolant temperature sensor is critical for proper engine management on this excavator. It provides real-time data that the ECM uses to adjust fuel injection timing, idle speed, and activate cooling system responses. On used Sumitomo excavators, this sensor and its associated wiring are particularly vulnerable to heat cycling damage and connector corrosion, making Code 1095 a relatively common issue in machines with higher operating hours.

Common Symptoms

When Code 1095 is active on your SH220LC-5, you may experience:

• Check engine light illuminated on the instrument panel with possible audible warning alarm
• Engine running rough or failing to reach proper operating temperature
• Excessive fuel consumption due to improper ECM compensation for perceived temperature
• Engine entering derate mode or limiting maximum RPM as a protective measure
• Cooling fan running continuously at high speed regardless of actual engine temperature

Potential Causes

Several factors can trigger Code 1095 on used Sumitomo excavators:

• Coolant temperature sensor failure due to internal element degradation (common after 5,000+ hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at connector pins
• Chafed wiring at known rub points near the engine block mounting brackets
• Corroded or loose ground connections affecting sensor circuit integrity
• Low coolant level causing intermittent sensor exposure and erratic readings
• Failed ECM (rare, but possible in high-hour machines with previous electrical issues)

How to Troubleshoot and Fix Code 1095

Step 1: Visual Inspection Begin by checking coolant level in the radiator and overflow tank. Inspect the coolant temperature sensor (typically located on the engine block near the thermostat housing) for physical damage, coolant leaks, or connector corrosion. On used excavators, carefully examine the wiring harness from sensor to ECM for abraded insulation, especially where it passes near moving components or sharp edges.

Step 2: Electrical Testing Disconnect the sensor connector and use a multimeter to check sensor resistance. At room temperature (68°F/20°C), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Test the harness continuity from sensor connector to ECM pins, checking for opens or shorts to ground. Measure supply voltage from the ECM (should be approximately 5 volts reference).

Step 3: Component Replacement and Verification If sensor resistance is out of specification or harness shows damage, replace the faulty component. When installing a new coolant temperature sensor, apply dielectric grease to connector terminals to prevent future corrosion—critical for used machines operating in harsh environments. Clear the fault code using diagnostic software (PC-based or compatible scan tool) and monitor for code recurrence during a complete heat cycle.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual for your specific machine serial number. If you're uncomfortable performing electrical diagnostics, consult a certified heavy equipment technician to prevent further damage to your excavator's control systems.