Sumitomo SH220LC-6 Fault Code 7248: Complete Diagnostic Guide

What is Sumitomo SH220LC-6 Fault Code 7248?

Fault Code 7248 on the Sumitomo SH220LC-6 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal temperature reading detected by the Engine Control Module (ECM). This code triggers when the ECM receives voltage signals outside the expected range from the coolant temperature sensor, suggesting either a sensor failure, wiring issue, or actual engine overheating condition.

This fault is critical for the SH220LC-6's performance because the ECM relies on accurate coolant temperature data to optimize fuel injection timing, manage engine protection protocols, and prevent catastrophic thermal damage. The Isuzu engine powering this excavator uses temperature readings to adjust performance parameters continuously. When this sensor circuit fails, the machine may enter derate mode or experience reduced hydraulic power to protect internal components.

Common Symptoms

When Code 7248 is active on your SH220LC-6, operators typically experience:

• Engine warning light illuminated on the instrument cluster with possible audible alarm
• Reduced engine power or hydraulic system performance (derate mode activation)
• Erratic temperature gauge readings showing abnormally high, low, or fluctuating temperatures
• Difficulty starting in cold conditions due to improper fuel mapping
• Black smoke from exhaust caused by incorrect fuel-to-air ratios based on faulty temperature data

Potential Causes

The most common technical causes for Code 7248 in used SH220LC-6 excavators include:

• Coolant temperature sensor failure due to thermal cycling and age-related deterioration
• Damaged or corroded wiring harness at the sensor connector, particularly where the harness routes near the engine block (known rub point)
• Broken or frayed wires in the sensor circuit between the ECM and sensor
• Corroded connector pins at the sensor plug from coolant leaks or moisture intrusion
• ECM internal fault (less common) affecting the temperature monitoring circuit
• Low coolant levels causing actual overheating and triggering legitimate high-temperature faults

How to Troubleshoot and Fix Code 7248

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block (typically on the thermostat housing). Check the wiring harness for visible damage, abrasion, or corrosion. On used excavators, pay special attention to areas where the harness contacts metal surfaces or heat shields—these are common failure points on the SH220LC-6.

Step 2: Test Sensor Resistance Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms (consult your service manual for exact specifications). Compare readings at different temperatures—resistance should decrease as temperature increases.

Step 3: Check Circuit Voltage With the sensor disconnected and ignition ON, measure voltage at the harness connector. You should see approximately 5 volts reference voltage from the ECM. If voltage is absent or incorrect, trace the wiring back to the ECM checking for breaks or shorts.

Step 4: Inspect Connectors Remove and carefully inspect both the sensor and ECM connectors for corrosion, bent pins, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease before reassembly.

Step 5: Replace Components If testing confirms sensor failure, replace with an OEM-quality coolant temperature sensor. For used machines, consider replacing the sensor connector pigtail simultaneously to prevent future corrosion issues. Clear codes using diagnostic software (Sumitomo diagnostic tool or compatible OBD scanner) and verify repair.

Disclaimer: This guide provides general diagnostic information. Always consult the official Sumitomo service manual for your specific serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.