Komatsu PC800LC-8R Fault Code E-19: Complete Diagnostic Guide

What is Komatsu PC800LC-8R Fault Code E-19?

Fault Code E-19 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°F to 300°F), or when circuit voltage falls outside specified parameters (usually 0.5V to 4.5V), the system triggers E-19. For the PC800LC-8R's SAA6D140E-5 engine, proper temperature monitoring is essential for protecting the high-pressure fuel system and preventing catastrophic engine damage that could cost $30,000+ in repairs.

Common Symptoms

When Code E-19 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 the engine
• Cooling fan running continuously at high speed regardless of actual temperature
• Difficulty starting in cold conditions or rough idle during warm-up
• Inaccurate temperature gauge readings showing extreme high or low values

Potential Causes

The most common technical causes for E-19 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 mounting brackets
• Corroded or loose connector pins at the sensor plug (common after 5,000+ operating hours)
• ECM internal circuit failure affecting the temperature monitoring input
• Coolant contamination causing sensor element coating or failure
• Damaged sensor threads allowing coolant leakage and false readings

How to Troubleshoot and Fix Code E-19

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block's coolant passage. Check for coolant leaks, damaged wiring, and connector corrosion. On used excavators, pay special attention to harness wear points where cables contact the engine block or frame rails.

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

Step 3: Live Circuit Testing With the sensor connected and ignition on (engine off), backprobe the sensor connector and measure supply voltage (should be approximately 5V from ECM). Monitor the signal voltage while warming the engine—it should decrease smoothly from ~3.5V (cold) to ~0.8V (operating temperature).

Step 4: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu sensor (Part #6754-81-7210 or equivalent). For used machines, always replace the connector pigtail if corrosion is present. Clear codes using Komatsu diagnostic software (KOMTRAX) and verify repair with a test cycle.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.