Komatsu PC800-8R Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC800-8R Fault Code E-17?

Fault Code E-17 on the Komatsu PC800-8R 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 PC800-8R's SAA6D140E-5 engine, proper temperature monitoring is essential for protecting the high-pressure fuel system and preventing catastrophic engine damage in demanding applications.

Common Symptoms

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

• Engine warning light illuminated on the monitor panel with audible alarm
• Engine derate mode activated, limiting maximum RPM to protect components
• Cooling fan running continuously at high speed regardless of actual temperature
• Difficulty starting in cold conditions or hard starting when engine is warm
• Erratic temperature gauge readings or gauge stuck at minimum/maximum position
• Potential black smoke from exhaust due to improper fuel mixture compensation

Potential Causes

The most common technical causes for E-17 on used PC800-8R excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 8,000+ hours)
• Corroded or loose connector pins at the sensor harness connection point
• Damaged wiring harness between sensor and ECM, particularly where harness routes near engine mounts (known rub point)
• Low coolant level causing sensor exposure to air instead of coolant
• ECM internal fault affecting the temperature monitoring circuit (rare but possible in high-hour machines)
• Contaminated coolant causing sensor element coating and inaccurate readings
• Aftermarket sensor installed during previous repairs with incorrect resistance specifications

How to Troubleshoot and Fix Code E-17

Step 1: Visual Inspection and Coolant Check

Begin by checking coolant level in the radiator and expansion tank. On used excavators, inspect the coolant temperature sensor (located on the engine block near the thermostat housing) for physical damage, coolant leaks, or corrosion. Examine the wiring harness from sensor to ECM for chafing, particularly where it passes near the engine mount bracket—a common wear point on PC800-8R models.

Step 2: Electrical Testing

Using a digital multimeter, disconnect the sensor connector and measure resistance across the sensor terminals. At 20°C (68°F), resistance should read approximately 2,000-3,000 ohms (consult service manual for exact specifications). Check harness continuity from sensor connector to ECM pins and verify no short to ground. Measure supply voltage at the harness connector with ignition on—should read approximately 5V reference voltage from ECM.

Step 3: Component Replacement and Verification

If sensor resistance is out of specification or harness shows damage, replace the faulty component with genuine Komatsu parts (part number 6732-81-3110 or equivalent). For used excavators, always apply dielectric grease to connector pins before reassembly to prevent future corrosion. Clear the fault code using Komatsu diagnostic software (KOMTRAX) or compatible scan tool, then run the engine through temperature cycles to verify repair.

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.