Komatsu PC800-7 Fault Code E116: Complete Diagnostic Guide

What is Komatsu PC800-7 Fault Code E116?

Fault Code E116 on the Komatsu PC800-7 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 is critical for the PC800-7's SAA6D140E-5 engine management system. It directly influences fuel injection timing, engine protection protocols, and hydraulic oil temperature regulation. When this sensor fails or provides inaccurate data, the ECM cannot properly manage engine performance, potentially leading to overheating, reduced power output, or automatic engine derate to prevent catastrophic damage.

Common Symptoms

When Code E116 is active, operators typically experience:

• Warning light illumination on the instrument cluster, often accompanied by an audible alarm
• Engine derate mode activation, limiting machine to 70-80% power output
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions
• Difficulty starting when the engine is cold, or excessive white smoke during warm-up
• Hydraulic system sluggishness due to ECM compensating for perceived temperature issues

Potential Causes

The most common technical reasons for E116 on used PC800-7 excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 8,000+ operating hours)
• Corroded or damaged wiring harness at connector points, especially near the engine block where heat cycling causes brittleness
• Shorted or open circuit in the sensor wiring, particularly at known rub points along the left side engine harness
• Contaminated coolant causing sensor element coating and inaccurate readings
• ECM internal fault (rare, but possible in high-hour machines with electrical system stress)
• Poor ground connections at the sensor mounting point or ECM ground straps

How to Troubleshoot and Fix Code E116

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block's thermostat housing. Check for physical damage, coolant leaks, or corrosion on the two-pin connector. On used excavators, examine the entire wiring harness for chafing, especially where it contacts the engine block or frame rails.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At 68°F (20°C), resistance should read approximately 2,000-3,000 ohms. Compare readings against Komatsu's specification chart. Next, check for continuity between the sensor connector pins and the ECM connector (typically 0.5-2 ohms). Inspect for short circuits to ground (should read infinite resistance).

Step 3: Live Voltage Testing With the ignition on and sensor disconnected, measure reference voltage at the harness connector. You should see approximately 5 volts on the signal wire. If voltage is absent or incorrect, trace the harness back to the ECM, checking for damaged wires or poor connections.

Step 4: Sensor Replacement and Verification If testing confirms sensor failure, replace with a genuine Komatsu part (P/N 6261-81-6510 or equivalent). Apply anti-seize compound to threads and torque to specification (typically 15-20 ft-lbs). After installation, clear codes using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then monitor for code recurrence during a full heat cycle.

Critical Note for Used Equipment: Before replacing components, thoroughly clean all electrical connectors with contact cleaner and inspect for green corrosion inside pins—a common issue on machines operating in humid environments or with coolant system leaks.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC800-7 service manual and consider professional assistance for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.