Sumitomo SH220LC-6 Fault Code 16: Complete Diagnostic Guide

What is Sumitomo SH220LC-6 Fault Code 16?

Fault Code 16 on the Sumitomo SH220LC-6 excavator indicates a malfunction in the engine coolant temperature sensor circuit. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage signal from the coolant temperature sensor, typically due to an open circuit, short circuit, or sensor failure.

The coolant temperature sensor is critical for the SH220LC-6's performance because it directly influences fuel injection timing, engine warm-up protocols, and protection against overheating. When the ECM cannot accurately read engine temperature, it defaults to a fixed value, which can cause poor fuel economy, rough idling, and potential engine damage if overheating occurs undetected.

Common Symptoms

When Code 16 is active on your Sumitomo SH220LC-6, you may experience:

• Check Engine Light or warning indicator illuminated on the instrument panel
• Difficulty starting the engine, especially in cold conditions
• Rough idle or poor acceleration due to incorrect fuel mapping
• Engine fan running continuously at high speed regardless of actual temperature
• Reduced engine performance or power output (derate mode in severe cases)

Potential Causes

The most common technical causes for Code 16 on used SH220LC-6 excavators include:

• Faulty coolant temperature sensor due to age-related degradation or thermal cycling damage
• Damaged wiring harness near the engine block where vibration and heat cause insulation breakdown
• Corroded or loose connector pins at the sensor or ECM connection points (common in machines with high operating hours)
• Open or short circuit in the sensor signal wire, often caused by harness rubbing against frame components
• ECM internal fault (rare, but possible in older machines with 8,000+ operating hours)

How to Troubleshoot and Fix Code 16

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor and its wiring harness for obvious damage. On used excavators, check for wire chafing near the thermostat housing and along the firewall routing path. Look for corrosion, oil contamination, or moisture in the connector.

Step 2: Electrical Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. A functional sensor typically reads 2,000-3,000 ohms at room temperature (consult your service manual for exact specifications). Check for continuity in the signal wire from sensor to ECM and verify no short to ground.

Step 3: Sensor and Harness Replacement If resistance is out of specification or wiring shows damage, replace the coolant temperature sensor (Sumitomo part or quality aftermarket equivalent). For used machines, consider replacing the entire sensor-to-ECM harness section if insulation is brittle or cracked. Clear the code using diagnostic software and verify proper operation.

Step 4: ECM Verification If the problem persists after sensor and wiring replacement, the ECM may require reprogramming or replacement—consult a Sumitomo-certified technician for advanced diagnostics.

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Disclaimer: This guide provides general troubleshooting information. Always consult your Sumitomo service manual and consider professional diagnostic assistance for complex electrical issues, especially on used equipment with unknown maintenance history.