Sumitomo SH210LC-5LR Fault Code 202: Complete Diagnostic Guide

What is Sumitomo SH210LC-5LR Fault Code 202?

Fault Code 202 on the Sumitomo SH210LC-5LR indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Electronic Control Module (ECM). This code typically triggers when the ECM receives voltage signals outside the normal operating range from the coolant temperature sensor (CTS), or when the sensor detects coolant temperatures exceeding safe operational limits.

The coolant temperature sensor plays a critical role in engine management by providing real-time data that affects fuel injection timing, idle speed control, and overheat protection systems. On used Sumitomo excavators, this code is particularly important because it can indicate either genuine overheating conditions that risk catastrophic engine damage or electrical faults that may cause unnecessary machine downtime.

Common Symptoms

When Code 202 is active on your SH210LC-5LR, you may experience:

• Engine warning light or coolant temperature warning light illuminated on the instrument cluster
• Engine derate mode activating, limiting RPM and hydraulic flow to prevent damage
• Erratic temperature gauge readings, fluctuating between normal and overheat zones
• Hard starting conditions or rough idle, especially when the engine is cold
• Cooling fan running continuously at high speed, even when coolant temperature appears normal

Potential Causes

The most common technical reasons for Code 202 on used SH210LC-5LR excavators include:

• Faulty coolant temperature sensor due to internal element degradation (common after 5,000+ operating hours)
• Corroded or damaged wiring harness connectors at the sensor, particularly where the harness routes near the engine block
• Chafed sensor wiring caused by rubbing against engine components or frame members during machine vibration
• Low coolant level or air pockets in the cooling system creating false temperature readings
• ECM internal fault or corrupted calibration data (less common but possible in high-hour machines)
• Genuine engine overheating due to clogged radiator, failed thermostat, or water pump issues

How to Troubleshoot and Fix Code 202

Step 1: Visual Inspection Begin with a thorough physical inspection. Check coolant level in the radiator and overflow tank—low coolant creates air pockets that cause erratic sensor readings. Inspect the coolant temperature sensor (typically located on the engine block near the thermostat housing) and its wiring harness for obvious damage, corrosion on connector pins, or oil contamination. On used excavators, pay special attention to harness routing where vibration causes wire insulation to wear through.

Step 2: Electrical Testing Using a digital multimeter, disconnect the coolant temperature sensor connector and measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Test the wiring harness for continuity between the sensor connector and ECM pins, and check for short circuits to ground. Resistance should be less than 5 ohms for continuity and infinite (open circuit) for ground shorts.

Step 3: Sensor Replacement and System Verification If sensor resistance values are out of specification or wiring shows damage, replace the faulty component. When installing a new coolant temperature sensor, apply thread sealant (not Teflon tape, which can contaminate the sensor). After replacement, bleed the cooling system properly to eliminate air pockets. Clear the fault code using Sumitomo diagnostic software or compatible scan tool, then operate the machine through a full heat cycle to verify the repair.

Important for Used Equipment: Before replacing expensive components, thoroughly clean all electrical connectors with electrical contact cleaner and apply dielectric grease. Many Code 202 instances on older machines resolve with connector maintenance alone, saving hundreds in unnecessary parts replacement.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.