Sumitomo SH220LC-6 Fault Code 193: Complete Diagnostic Guide

What is Sumitomo SH220LC-6 Fault Code 193?

Fault Code 193 on the Sumitomo SH220LC-6 excavator indicates a malfunction in the engine coolant temperature (ECT) sensor circuit or an abnormal temperature reading detected by the engine control module (ECM). This code specifically signals that the ECM has detected either an out-of-range voltage signal from the coolant temperature sensor or a reading that doesn't correlate with actual operating conditions.

The ECT sensor plays a critical role in the SH220LC-6's engine management system by providing real-time coolant temperature data to the ECM. This information directly influences fuel injection timing, idle speed control, and emission system operation. On used excavators, this sensor becomes increasingly vulnerable to failure due to corrosion, thermal cycling stress, and coolant contamination over thousands of operating hours.

Common Symptoms

When Code 193 is active on your SH220LC-6, you may experience:

• Check engine light or warning indicator illuminated on the instrument cluster
• Hard starting conditions, especially during cold starts when the ECM cannot properly adjust fuel delivery
• Erratic idle speed or engine hunting as the ECM defaults to predetermined temperature values
• Poor fuel economy and black smoke from exhaust due to improper fuel mixture compensation
• Engine overheating without warning if the sensor fails to report actual high temperatures

Potential Causes

The most common technical reasons for Code 193 on used SH220LC-6 excavators include:

• Faulty ECT sensor – internal resistance drift or complete failure due to age and thermal stress
• Damaged wiring harness – particularly at flex points near the engine block where vibration causes wire chafing
• Corroded or loose electrical connectors – moisture intrusion in the sensor connector pins
• ECM internal fault – less common but possible in high-hour machines with electrical system degradation
• Coolant contamination affecting sensor accuracy – buildup of scale or electrolysis corrosion on sensor tip
• Open or short circuit in the sensor signal wire between the sensor and ECM

How to Troubleshoot and Fix Code 193

Step 1: Visual Inspection Begin by locating the ECT sensor (typically mounted on the engine block or thermostat housing). Inspect the sensor connector for corrosion, bent pins, or moisture. Check the wiring harness for obvious damage, especially where it routes along the engine. On used excavators, pay special attention to harness routing near hot exhaust components or sharp edges where insulation may have worn through.

Step 2: Sensor Resistance Testing Disconnect the ECT sensor connector and use a digital multimeter to measure resistance across the sensor terminals. For the SH220LC-6, typical resistance should be approximately 2,000-3,000 ohms at 20°C (68°F), decreasing as temperature rises. Compare your readings against Sumitomo specifications. If resistance is infinite (open circuit) or near zero (short circuit), replace the sensor.

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

Step 4: Verify Repair and Clear Code After replacing faulty components, use Sumitomo diagnostic software or a compatible scan tool to clear the fault code. Run the engine through a complete warm-up cycle and monitor for code recurrence. On high-hour used machines, consider applying dielectric grease to connectors to prevent future corrosion.

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Disclaimer: This guide provides general diagnostic information for Sumitomo SH220LC-6 excavators. Always consult the manufacturer's service manual for model-specific procedures and specifications. If you're uncomfortable performing electrical diagnostics, seek assistance from a qualified heavy equipment technician to prevent further damage to the machine's electrical system.