Sumitomo SH210-6 Fault Code 202: Complete Diagnostic Guide

What is Sumitomo SH210-6 Fault Code 202?

Fault Code 202 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 typically triggers when the ECM receives voltage signals outside the expected range from the coolant temperature sensor (CTS), suggesting either a sensor failure, wiring issue, or actual overheating condition.

This fault is critical because the ECM relies on accurate coolant temperature data to regulate fuel injection timing, idle speed, and engine protection protocols. On used excavators like the SH210-6, ignoring this code can lead to improper fuel combustion, reduced hydraulic performance, or catastrophic engine damage from undetected overheating.

Common Symptoms

When Code 202 is active on your Sumitomo SH210-6, you may experience:

• Check engine light or malfunction warning lamp illuminated on the instrument panel
• Engine running in limp mode or derate condition with reduced power output
• Erratic engine idle or difficulty starting, especially when cold
• Cooling fan running continuously at high speed regardless of actual temperature
• Inaccurate temperature gauge readings or gauge remaining at cold position

Potential Causes

The most common technical reasons for Code 202 on used SH210-6 excavators include:

• Failed coolant temperature sensor due to internal resistance drift (common after 5,000+ hours)
• Damaged wiring harness or corroded connectors between the sensor and ECM, particularly at rub points near the engine block
• Shorted or open circuits in the sensor signal wire caused by insulation breakdown
• Low coolant level exposing the sensor element to air instead of coolant
• ECM internal fault (rare, but possible on high-hour machines)
• Contaminated coolant causing sensor coating buildup affecting readings

How to Troubleshoot and Fix Code 202

Step 1: Visual Inspection Locate the coolant temperature sensor (typically mounted on the engine block near the thermostat housing). Inspect the wiring harness for visible damage, chafing, or corrosion on the connector. On used excavators, check for coolant leaks around the sensor that may indicate seal failure.

Step 2: Check Coolant Level Verify proper coolant level when the engine is cold. Low coolant can cause false readings. Top off if necessary and check for leaks.

Step 3: Test Sensor Resistance Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. Compare readings at different temperatures against manufacturer specifications (typically 2,000-3,000 ohms at 68°F/20°C). Replace the sensor if readings are out of range.

Step 4: Verify Wiring Continuity With the sensor disconnected, check for continuity between the sensor connector and ECM pins. Test for short circuits to ground. Repair or replace damaged harness sections, paying special attention to areas where the harness contacts metal surfaces.

Step 5: Clear Code and Monitor After repairs, use diagnostic software compatible with Sumitomo systems to clear the fault code. Run the machine through operating temperature cycles and monitor for code recurrence.

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Disclaimer: This guide provides general diagnostic information for Sumitomo SH210-6 excavators. Always consult the manufacturer's service manual and consider professional assessment, especially for used equipment with unknown maintenance history. Improper diagnostics can lead to further damage.