Sumitomo SH260LC-6 Fault Code 202: Complete Diagnostic Guide

What is Sumitomo SH260LC-6 Fault Code 202?

Fault Code 202 on the Sumitomo SH260LC-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 diagnostic trouble code (DTC) is triggered when the ECM receives voltage signals outside the expected range from the coolant temperature sensor, or when the sensor detects coolant temperatures exceeding safe operating parameters.

This code is critical for the SH260LC-6 because the ECM relies on accurate coolant temperature data to manage fuel injection timing, engine protection protocols, and hydraulic system performance. When this sensor fails or provides erratic readings, the excavator may enter derate mode to prevent catastrophic engine damage from overheating or run inefficiently due to incorrect fuel mapping.

Common Symptoms

• Engine warning light illuminated on the instrument cluster with reduced engine power output
• Engine derate mode activated, limiting RPM to 1200-1500 range to protect components
• Erratic temperature gauge readings that fluctuate rapidly or show unrealistic values (extremely high or low)
• Difficulty starting when the engine is cold, or excessive black smoke during warm-up cycles
• Cooling fan running continuously at maximum speed regardless of actual engine temperature

Potential Causes

The most common technical causes for Code 202 on used SH260LC-6 excavators include:

• Coolant temperature sensor failure due to internal resistance drift or element degradation (common after 5,000+ operating hours)
• Wiring harness damage at the sensor connector or along the harness routing near the engine block where vibration and heat cause insulation breakdown
• Corroded or loose electrical connections at the sensor plug or ECM connector terminals (especially in machines exposed to harsh environments)
• ECM internal fault affecting the temperature sensor input circuit (less common but possible in high-hour machines)
• Actual engine overheating caused by cooling system failures (low coolant, failed thermostat, blocked radiator)

How to Troubleshoot and Fix Code 202

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for physical damage, coolant leaks around the sensor base, and examine the wiring harness for abraded insulation, particularly where it contacts the engine or frame. On used excavators, inspect connector pins for corrosion or bent terminals caused by previous removal attempts.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. A functional sensor typically reads 2,000-3,000 ohms at room temperature (68°F/20°C). Compare readings against Sumitomo specifications. Next, check the wiring harness for continuity between the sensor connector and ECM, and verify no short-to-ground conditions exist (should read infinite resistance to chassis ground).

Step 3: Live Data Analysis Connect Sumitomo diagnostic software or a compatible scan tool to monitor real-time coolant temperature values. Compare the sensor reading with an infrared thermometer measurement of the actual coolant temperature. If readings differ by more than 10°F, replace the sensor. Clear codes and perform a cold-start test cycle to verify the repair.

Step 4: Component Replacement If sensor and wiring tests pass but the code persists, inspect the ECM connectors for moisture intrusion or terminal corrosion. In high-hour used machines, consider replacing the entire sensor-to-ECM harness section if multiple rub points or repairs are evident.

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Disclaimer: This guide provides general troubleshooting information. Always consult the Sumitomo SH260LC-6 service manual and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.