Komatsu PC800SE-7 Fault Code E113: Complete Diagnostic Guide

What is Komatsu PC800SE-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 temperature monitoring system that protects the Komatsu SAA6D140E-7 engine from overheating damage.

The coolant temperature sensor sends voltage signals to the ECM, which uses this data to regulate fuel injection timing, fan speed, and engine protection protocols. When the ECM detects voltage readings outside the normal range (typically 0.5-4.5V) or physically impossible temperature values, it triggers E113. For the PC800SE-7, this is critical because improper temperature management can lead to severe engine damage, reduced hydraulic efficiency, and costly downtime on high-hour used machines.

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 automatic derate mode to prevent overheating damage
• Inaccurate temperature gauge readings (stuck at cold, hot, or fluctuating erratically)
• Cooling fan running continuously at maximum speed regardless of actual engine temperature
• Difficulty starting in cold conditions if ECM reads false high-temperature signals

Potential Causes

The most common technical causes for E113 on used PC800SE-7 excavators include:

• Faulty coolant temperature sensor due to internal resistance drift (common after 8,000+ operating hours)
• Damaged or corroded wiring harness between sensor and ECM, particularly at connector pins
• Harness chafing near the engine block mounting points—a known wear point on this model
• Corroded or loose connector terminals at the sensor or ECM interface due to coolant leaks or moisture intrusion
• ECM internal fault (rare, but possible in high-hour machines with electrical system stress)
• Low coolant level causing actual overheating and legitimate sensor response

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) for physical damage, coolant leaks, or corrosion. On used excavators, carefully examine the wiring harness for rubbing, cracking, or exposure near hot engine components.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms (consult Komatsu specifications). Check harness continuity from sensor to ECM connector and verify no shorts to ground. Inspect connector pins for corrosion or bent terminals—common issues in older machines.

Step 3: Advanced Diagnostics Connect Komatsu diagnostic software (KOMTRAX Plus or equivalent) to monitor live sensor voltage while the engine warms up. Normal voltage should decrease smoothly from ~3.5V (cold) to ~0.5V (hot). Erratic readings indicate sensor failure; no change suggests open circuit in wiring. For used equipment, always clean and apply dielectric grease to connectors before replacing components.

Step 4: Component Replacement If testing confirms sensor failure, replace with genuine Komatsu parts (part number varies by engine serial). Clear codes using diagnostic software and perform a test run, monitoring temperature behavior under load.

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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 seek qualified diesel technician assistance for complex electrical repairs.