Komatsu PC800-8R Fault Code E-19: Complete Diagnostic Guide

What is Komatsu PC800-8R Fault Code E-19?

Fault Code E-19 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-19. For the PC800-8R's high-performance diesel engine, accurate temperature monitoring is essential to prevent catastrophic engine damage and maintain hydraulic system efficiency.

Common Symptoms

When Code E-19 is active, operators typically experience:

• Engine warning light illuminated on the instrument panel, often accompanied by an audible alarm
• Reduced engine power or automatic derate mode activation to protect the engine from potential overheating
• Cooling fan running continuously at maximum speed, regardless of actual engine temperature
• Difficulty starting the engine, particularly in cold weather conditions
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions

Potential Causes

The most common technical causes for E-19 on used PC800-8R excavators include:

• Faulty coolant temperature sensor due to internal element degradation or contamination from coolant additives
• Damaged wiring harness between the sensor and ECM, particularly at known rub points near the engine mounting brackets and along the frame rail
• Corroded or loose electrical connectors at the sensor or ECM interface, common in machines with high operating hours
• Low coolant level causing intermittent sensor exposure and erratic readings
• ECM internal fault or corrupted calibration data (less common but possible in older units)
• Aftermarket coolant incompatibility causing sensor coating buildup

How to Troubleshoot and Fix Code E-19

Step 1: Visual Inspection Begin by checking the 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 from sensor to ECM for chafing, cuts, or heat damage at known wear points.

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 typically read 2,000-3,000 ohms (consult your service manual for exact specifications). Check circuit continuity from the sensor connector to the ECM. Measure supply voltage at the sensor connector with ignition on—it should read approximately 5 volts.

Step 3: Component Replacement and Verification If resistance values are out of specification or the harness shows damage, replace the faulty component. For used machines, always clean connector terminals with electrical contact cleaner and apply dielectric grease before reconnection. Clear the fault code using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then monitor for code recurrence during a complete heat cycle.

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 or if you're uncertain about any procedure.