Komatsu PC800LC-8R Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC800LC-8R Fault Code E-17?

Fault Code E-17 on the Komatsu PC800LC-8R 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 monitoring system, which is critical for preventing engine overheating and maintaining optimal operating temperatures.

The ECM continuously monitors signals from the coolant temperature sensor to regulate fuel injection timing, engine speed, and cooling fan operation. When the sensor provides readings outside the normal operating range (typically -40°C to 150°C), or when circuit voltage falls outside specified parameters (usually 0.5V to 4.5V), the system triggers E-17. For the PC800LC-8R's SAA6D140E-5 engine, proper temperature monitoring is essential for protecting this high-output powerplant from thermal damage and maintaining hydraulic system efficiency.

Common Symptoms

When Code E-17 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with audible alarm
• Reduced engine power or automatic derate mode to prevent overheating damage
• Cooling fan running continuously at maximum speed regardless of actual temperature
• Difficulty starting in cold conditions or rough idle when engine is cold
• Inaccurate temperature gauge readings showing extreme high or low values inconsistent with actual operating conditions

Potential Causes

The most common technical causes for E-17 on used PC800LC-8R excavators include:

• Coolant temperature sensor failure due to age-related degradation or thermal cycling damage
• Wiring harness damage at known rub points near the engine block or turbocharger heat shield
• Corroded or loose connector pins at the sensor or ECM connection points (common in high-hour machines)
• ECM internal circuit failure affecting the temperature monitoring input channel
• Coolant contamination causing sensor element fouling or coating
• Damaged sensor mounting threads allowing coolant leaks and false readings

How to Troubleshoot and Fix Code E-17

Step 1: Visual Inspection Begin by locating the coolant temperature sensor on the engine block (typically near the thermostat housing). Inspect the wiring harness for obvious damage, chafing, or heat damage. Check the connector for corrosion, bent pins, or coolant intrusion. On used excavators, pay special attention to harness routing near moving components or heat sources.

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 service manual for exact specifications). Check circuit voltage at the harness connector with ignition on—you should see approximately 5V reference voltage from the ECM.

Step 3: Circuit Continuity Check Test wiring continuity between the sensor connector and ECM pins using the machine's wiring diagram. Check for short circuits to ground or power. Inspect for intermittent connections by wiggling harnesses while monitoring voltage.

Step 4: Component Replacement If sensor resistance is out of specification or wiring shows damage, replace the faulty component using genuine Komatsu parts (part number 6261-81-6510 or equivalent). Always apply thread sealant to prevent coolant leaks. Clear codes using Komatsu diagnostic software (KOMTRAX) and verify repair with a test run.

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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 professional assistance from certified technicians for complex repairs.