Komatsu PC800-7 Fault Code E113: Complete Diagnostic Guide

What is Komatsu PC800-7 Fault Code E113?

Fault Code E113 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the Engine Control Module (ECM). This code specifically relates to the coolant temperature sensor sending irregular voltage signals outside the manufacturer's specified parameters, typically between 0.5-4.5 volts.

The coolant temperature sensor plays a critical role in the PC800-7's SAA6D140E-5 engine management system. It directly influences fuel injection timing, engine protection protocols, and hydraulic system performance. When this sensor fails or provides inaccurate data, the ECM cannot properly regulate engine temperature, potentially leading to overheating, reduced power output, or premature component wear—particularly critical concerns in high-hour used excavators.

Common Symptoms

When Code E113 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Reduced engine power or derate mode activation to prevent overheating damage
• Erratic temperature gauge readings showing unusually high, low, or fluctuating temperatures
• Difficulty starting in cold conditions due to incorrect fuel enrichment
• Increased fan engagement or cooling system running continuously regardless of actual temperature

Potential Causes

The most common technical causes for E113 on used PC800-7 excavators include:

• Faulty coolant temperature sensor (internal resistance degradation common after 8,000+ hours)
• Damaged or corroded wiring harness at sensor connector—known rub point near engine mount bracket
• Corroded sensor connector pins due to coolant seepage or environmental exposure
• Open or short circuit in wiring between sensor and ECM (pin 47 on ECM connector)
• ECM internal fault (rare, but possible in high-hour machines)
• Low coolant level causing sensor exposure and false readings
• Contaminated coolant affecting sensor accuracy

How to Troubleshoot and Fix Code E113

Step 1: Visual Inspection Begin by checking coolant level in the radiator and overflow tank. Inspect the coolant temperature sensor (located on the engine block near the thermostat housing) and its wiring harness for obvious damage, corrosion, or coolant leaks. On used excavators, pay special attention to harness routing where it contacts the engine mount—a common wear point.

Step 2: Electrical Testing Disconnect the sensor connector and inspect pins for corrosion or bent contacts. Using a digital multimeter, measure sensor resistance: at 20°C (68°F), resistance should read approximately 2,000-3,000 ohms; at 80°C (176°F), approximately 300-400 ohms. Check wiring continuity from sensor to ECM pin 47 (should read less than 5 ohms resistance).

Step 3: Voltage Signal Verification With ignition on and sensor connected, backprobe the sensor signal wire using a multimeter or Komatsu diagnostic software (KOMTRAX) to verify voltage output ranges between 0.5-4.5 volts and changes smoothly with temperature. Erratic readings indicate sensor replacement; stable but incorrect readings suggest wiring issues or ECM problems.

Step 4: Component Replacement Replace the coolant temperature sensor (Komatsu part number 6732-81-3140 or equivalent) if testing confirms failure. For used machines, always replace the connector pigtail simultaneously to prevent future corrosion issues. Clear codes using diagnostic software and verify proper operation through a complete heat cycle.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.