What is Sumitomo SH220LC-6 Fault Code 7250?

Fault Code 7250 on the Sumitomo SH220LC-6 excavator indicates a malfunction in the engine coolant temperature (ECT) sensor circuit or an abnormal coolant temperature reading detected by the engine control module (ECM). This diagnostic trouble code (DTC) typically triggers when the ECM receives voltage signals outside the normal operating range from the coolant temperature sensor, suggesting either a sensor failure, wiring issue, or actual engine overheating condition.

The ECT sensor plays a critical role in the SH220LC-6's performance by providing real-time temperature data that the ECM uses to adjust fuel injection timing, idle speed, and cooling fan operation. When this sensor circuit fails, the engine may run inefficiently, consume excessive fuel, or enter a protective derate mode to prevent catastrophic engine damage. For used excavators operating in demanding conditions, this code requires immediate attention to avoid expensive engine repairs.

Common Symptoms

• Check engine light or warning lamp illuminated on the instrument cluster
• Engine running hotter than normal or cooling fan running continuously even during light operation
• Hard starting when the engine is cold, or rough idle during warm-up periods
• Reduced engine power or derate mode activation limiting hydraulic performance
• Excessive black smoke from the exhaust due to improper fuel-air mixture adjustments

Potential Causes

The most common technical causes for Code 7250 on used SH220LC-6 excavators include:

• Failed coolant temperature sensor due to age-related degradation or thermal cycling damage
• Corroded or loose electrical connectors at the sensor or ECM harness connection points
• Damaged wiring harness with chafed insulation or broken conductors, particularly near engine mounting points where vibration causes wear
• Low coolant level or contaminated coolant affecting sensor accuracy
• ECM ground circuit failure creating voltage reference problems
• Actual engine overheating caused by clogged radiator, failed thermostat, or water pump issues

How to Troubleshoot and Fix Code 7250

Step 1: Visual Inspection Begin by checking the coolant level in the radiator and overflow tank. Inspect the ECT sensor (typically located near the thermostat housing) and its electrical connector for visible corrosion, oil contamination, or physical damage. On used machines, pay special attention to the wiring harness routing near the engine block where friction against metal surfaces commonly causes insulation wear.

Step 2: Electrical Testing Using a digital multimeter, disconnect the ECT sensor connector and measure the sensor resistance. At 68°F (20°C), resistance should typically read between 2,000-3,000 ohms (consult the Sumitomo service manual for exact specifications). Test the harness voltage with the key on, engine off—you should see approximately 5 volts reference voltage from the ECM. Check for continuity in the ground circuit and signal wire back to the ECM.

Step 3: Component Replacement and Verification If resistance values are out of specification or the sensor shows open or short circuit readings, replace the ECT sensor with an OEM or high-quality aftermarket unit. Before installation, clean the sensor mounting threads and apply a thin coat of heat-conductive paste. After replacement, clear the fault code using Sumitomo diagnostic software or a compatible scan tool, then run the engine through a complete heat cycle to verify the repair.

Step 4: Address Root Causes in Used Equipment For older SH220LC-6 excavators, inspect the entire engine harness for age-related deterioration, especially at connector boots and wire tie points. Replace any corroded connectors and apply dielectric grease to prevent future moisture intrusion. Verify the cooling system is functioning properly by pressure testing and confirming the thermostat opens at the correct temperature.

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Disclaimer: This guide provides general troubleshooting information for educational purposes. Always consult the official Sumitomo service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may void warranties or cause additional equipment damage.