Sumitomo SH200-5 Fault Code 1345: Technical Guide for Diagnosis and Repair

What is Sumitomo SH200-5 Fault Code 1345?

Fault Code 1345 on the Sumitomo SH200-5 excavator indicates a malfunction in the engine coolant temperature sensor circuit or an out-of-range coolant temperature reading detected by the engine control module (ECM). This code typically triggers when the ECM receives voltage signals outside the normal operating parameters (usually 0.5-4.5V) from the coolant temperature sensor (CTS), or when sensor circuit continuity is compromised.

This fault is critical for the SH200-5's performance because the ECM relies on accurate coolant temperature data to manage fuel injection timing, engine warm-up cycles, and prevent overheating conditions. Ignoring this code can lead to improper engine operation, reduced fuel efficiency, and potential catastrophic engine damage from thermal stress.

Common Symptoms

When Code 1345 is active, operators typically experience:

• Check engine light or warning lamp illuminated on the instrument panel
• Engine operating in derate mode with reduced power output, particularly under load
• Difficulty starting in cold conditions or extended cranking times
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Erratic temperature gauge readings or gauge stuck at cold/hot positions
• Black smoke from exhaust due to improper fuel mixture compensation

Potential Causes

The most common technical causes for Code 1345 on used SH200-5 excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 5,000+ operating hours)
• Damaged or corroded wiring harness connections at the sensor plug, particularly where the harness routes near the engine block and experiences heat cycling
• Chafed wires along known rub points between the engine and chassis frame rails
• Corroded ECM connector pins (specifically the temperature sensor input terminals)
• Contaminated coolant causing sensor element coating and false readings
• ECM internal fault affecting the sensor input circuit (rare, but possible in high-hour machines)

How to Troubleshoot and Fix Code 1345

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor location (typically on the thermostat housing or cylinder head). Check for physical damage, coolant leaks around the sensor base, and examine the connector for corrosion, bent pins, or moisture intrusion. On used excavators, pay special attention to harness routing where wires contact hot engine surfaces or sharp edges.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. At room temperature (20°C/68°F), resistance should typically read 2,000-3,000 ohms (consult 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 (should read infinite resistance).

Step 3: Signal Voltage Check With the ignition on and sensor connected, backprobe the sensor connector and measure voltage. You should see approximately 5V reference voltage from the ECM. The return signal voltage should change smoothly as engine temperature rises (higher temperature = lower voltage). Erratic readings indicate sensor replacement is needed.

Step 4: Repair and Verification Replace faulty components—for used machines, consider replacing both the sensor and connector pigtail simultaneously to prevent repeat failures. Clear codes using diagnostic software (Sumitomo-compatible scan tool), and verify proper coolant level and mixture. Monitor operation through several heat cycles to confirm repair.

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Disclaimer: This guide provides general diagnostic information. Always consult the Sumitomo SH200-5 service manual for exact specifications. Complex electrical issues should be diagnosed by qualified heavy equipment technicians with proper diagnostic equipment.