Komatsu PC800SE-7 Fault Code E116: Complete Diagnostic Guide

What is Komatsu PC800SE-7 Fault Code E116?

Fault Code E116 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 provides critical data to the ECM, which uses this information to adjust fuel injection timing, control engine speed, and activate warning systems. When E116 triggers, the ECM detects either an out-of-range voltage signal, an open/short circuit, or implausible temperature readings that don't correlate with actual operating conditions. For the PC800SE-7, this is particularly critical because improper temperature management can lead to severe engine damage, reduced hydraulic performance, and costly downtime on high-value used equipment.

Common Symptoms

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Engine derate mode activated, limiting maximum RPM and hydraulic power output
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Difficulty starting in cold conditions or excessive white smoke during warm-up

Potential Causes

The most common technical causes for E116 on used PC800SE-7 excavators include:

• Faulty coolant temperature sensor due to age-related degradation or internal element failure
• 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 5,000+ hours)
• ECM internal fault affecting the temperature input circuit
• Coolant contamination causing sensor element coating or failure
• Ground circuit issues specific to the engine harness grounding points

How to Troubleshoot and Fix Code E116

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block (typically near the thermostat housing). Check for physical damage, coolant leaks, or corrosion. On used excavators, examine the wiring harness for rub points against the engine block, cracked insulation, or heat damage—common wear areas include routing near the turbocharger and exhaust manifold.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At 20°C (68°F), resistance should typically read 2,000-3,000 ohms (consult your service manual for exact specifications). Test the harness continuity from sensor connector to ECM pin, checking for opens or shorts to ground. Measure supply voltage at the sensor connector with ignition on—should read approximately 5 volts.

Step 3: Advanced Diagnostics Connect Komatsu KOMTRAX or compatible diagnostic software to monitor live sensor data. Compare coolant temperature readings with actual engine temperature using an infrared thermometer. If readings differ by more than 10°C, replace the sensor. For used machines, clean all connector terminals with electrical contact cleaner and apply dielectric grease before reassembly.

Step 4: Component Replacement If testing confirms sensor failure, replace with genuine Komatsu parts (part number specific to PC800SE-7). After replacement, clear codes, run the engine through a complete heat cycle, and verify proper operation.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number. Complex electrical issues may require professional diagnosis with factory-level diagnostic equipment.