Sumitomo SH210-6 Fault Code 193: Complete Diagnostic Guide

What is Sumitomo SH210-6 Fault Code 193?

Fault Code 193 on the Sumitomo SH210-6 excavator 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 triggers when the ECM receives voltage signals outside the expected range from the coolant temperature sensor, typically indicating either sensor failure, wiring issues, or actual overheating conditions.

This fault is critical for the SH210-6 because the coolant temperature sensor provides essential data that the ECM uses to regulate fuel injection timing, idle speed, and engine protection protocols. When this sensor circuit fails, the excavator may enter derate mode or experience erratic engine performance, directly impacting productivity and potentially causing severe engine damage if actual overheating goes undetected.

Common Symptoms

When Code 193 is active on your Sumitomo SH210-6, operators typically experience:

• Engine warning light illuminated on the instrument cluster
• Reduced engine power or derate mode activation, limiting maximum RPM
• Hard starting conditions, especially when the engine is cold
• Black smoke from exhaust due to improper fuel-air mixture calibration
• Erratic idle speed or engine hunting at low RPM
• Cooling fan running continuously regardless of actual engine temperature

Potential Causes

Based on common failures in used SH210-6 excavators, Code 193 typically results from:

• Coolant temperature sensor failure due to age-related degradation or thermal cycling stress
• Damaged wiring harness near the thermostat housing where heat and vibration cause insulation breakdown
• Corroded connector pins at the sensor plug, common in machines with coolant leaks or high-hour usage
• ECM internal circuit malfunction (less common but possible in high-hour machines)
• Poor ground connections on the engine block affecting sensor signal return
• Contaminated coolant causing sensor element coating and inaccurate readings

How to Troubleshoot and Fix Code 193

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located near the thermostat housing on the engine block. Check for coolant leaks, damaged wiring, or corroded connectors. On used excavators, pay special attention to harness rub points where the wiring contacts metal surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At room temperature (68°F/20°C), resistance should typically read 2,000-3,000 ohms. Compare readings against manufacturer specifications. Check supply voltage at the connector—should read approximately 5 volts with ignition on.

Step 3: Wiring Continuity Check Test continuity between the sensor connector and the ECM harness. Check for shorts to ground or power. Inspect the ground circuit thoroughly, as poor grounds are common in older machines.

Step 4: Connector Service Clean all connector pins with electrical contact cleaner and inspect for corrosion or bent terminals. Apply dielectric grease to prevent future moisture intrusion.

Step 5: Component Replacement If sensor readings are out of specification, replace the coolant temperature sensor with an OEM or quality aftermarket part. After replacement, clear codes using diagnostic software and verify proper operation.

Disclaimer: This guide provides general diagnostic information. Always consult the Sumitomo service manual for your specific serial number and seek professional assistance for complex electrical diagnostics or repairs beyond your expertise level.