Sumitomo SH290-5 Fault Code 113: Complete Diagnostic Guide

What is Sumitomo SH290-5 Fault Code 113?

Fault Code 113 on the Sumitomo SH290-5 excavator indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM).

This diagnostic trouble code (DTC) specifically monitors the coolant temperature sensor circuit for voltage irregularities, open circuits, short circuits, or sensor readings that fall outside the manufacturer's predetermined operating range (typically -40°C to 150°C). The ECT sensor plays a critical role in the SH290-5's engine management system, directly affecting fuel injection timing, combustion efficiency, and emissions control. When this code activates, the ECM may default to a predetermined coolant temperature value, which can compromise engine performance and potentially lead to overheating or inefficient fuel consumption on used machines with accumulated operating hours.

Common Symptoms

When Code 113 is active on your Sumitomo SH290-5, you may experience:

• Engine warning light or check engine indicator illuminated on the instrument panel
• Poor cold-start performance with excessive cranking time or rough idling during warm-up
• Black smoke from the exhaust due to improper fuel-air mixture calibration
• Engine derate mode or reduced power output as the ECM enters protective operational parameters
• Inaccurate temperature gauge readings showing erratic fluctuations or stuck readings on the display

Potential Causes

The most common technical causes for Code 113 on used SH290-5 excavators include:

• Failed or degraded ECT sensor due to age, thermal cycling stress, or internal element corrosion
• Damaged wiring harness at known rub points near the engine block or valve cover where vibration causes insulation wear
• Corroded or loose electrical connectors at the sensor plug, particularly on machines operated in wet or marine environments
• Short circuit to ground caused by chafed wires contacting metal surfaces along the harness routing path
• ECM internal fault (less common) affecting the sensor signal processing circuit
• Low coolant level causing sensor exposure to air instead of coolant, producing erratic voltage signals

How to Troubleshoot and Fix Code 113

Step 1: Visual Inspection Begin by inspecting the ECT sensor (located on the engine block near the thermostat housing) and its wiring harness. Check for obvious damage, coolant leaks around the sensor base, corroded connector pins, or abraded wire insulation. On used excavators, pay special attention to harness routing where it passes over engine mounts or near moving components.

Step 2: Electrical Testing Using a digital multimeter (DMM), disconnect the ECT sensor connector and measure resistance across the sensor terminals. At room temperature (20°C), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Test the harness side for continuity to the ECM and check for short circuits to ground (should read infinite resistance).

Step 3: Voltage Signal Verification With the ignition on but engine off, backprobe the sensor connector and measure the reference voltage from the ECM (typically 5 volts). If voltage is absent or incorrect, trace the harness for breaks or check ECM connector integrity.

Step 4: Component Replacement If the sensor fails resistance testing or the harness shows damage, replace the faulty component using OEM or high-quality aftermarket parts. After installation, clear the fault code using diagnostic software (Sumitomo-compatible scan tool) and perform a test cycle to verify the repair.

Used Equipment Consideration: Before replacing the ECT sensor, inspect the coolant condition and verify proper system fill level, as old coolant with reduced anti-corrosion properties can accelerate sensor failure in aging machines.

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Disclaimer: This guide provides general diagnostic information for the Sumitomo SH290-5. Always consult the manufacturer's official service manual and consider professional diagnostic assistance for complex electrical issues or if you lack proper testing equipment.