Komatsu PC650LC-8R Fault Code E-19: Complete Diagnostic Guide

What is Komatsu PC650LC-8R Fault Code E-19?

Fault Code E-19 on the Komatsu PC650LC-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 sensor sending irregular voltage signals or detecting temperatures outside the normal operating parameters.

The coolant temperature sensor plays a critical role in the PC650LC-8R's SAA6D140E-6 engine management system. It provides real-time data to the ECM for fuel injection timing, engine protection protocols, and hydraulic system temperature compensation. When this sensor fails or sends erratic signals, the machine's performance and longevity are directly compromised, potentially leading to overheating, reduced power output, or complete engine shutdown.

Common Symptoms

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

• Warning light illumination on the monitor panel, often accompanied by an audible alarm
• Engine derate mode where maximum RPM is limited to protect components from thermal damage
• Erratic temperature gauge readings that fluctuate abnormally or show implausible values
• Difficulty starting in cold conditions due to incorrect fuel enrichment calculations
• Reduced hydraulic response as the system enters protective mode based on false temperature data

Potential Causes

The most common technical causes for E-19 on used PC650LC-8R excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 8,000+ operating hours)
• Corroded or loose connector pins at the sensor harness connection point near the thermostat housing
• Damaged wiring harness from rubbing against the engine block or exhaust components—a known wear point on this model
• ECM internal fault affecting the sensor input circuit (less common but possible in high-hour machines)
• Contaminated coolant causing sensor element coating and inaccurate readings
• Poor ground connection at the sensor or ECM mounting points

How to Troubleshoot and Fix Code E-19

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for physical damage, coolant leaks, or corrosion on the connector pins. On used excavators, pay special attention to harness chafing where wires route near moving components or sharp edges.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. At 20°C (68°F), resistance should typically read 2,000-3,000 ohms (consult your service manual for exact specifications). Test the harness voltage with the key on, engine off—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Signal Testing Reconnect the sensor and use Komatsu KOMTRAX diagnostic software or a compatible scan tool to monitor live coolant temperature data. Compare readings with an infrared thermometer measurement of the actual engine temperature. A variance greater than 10°C indicates sensor replacement is necessary.

Step 4: Connector and Ground Verification Clean all connector terminals with electrical contact cleaner and apply dielectric grease. Verify the ground circuit continuity between the sensor ground pin and the ECM ground—resistance should be less than 1 ohm.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Komatsu coolant temperature sensor (Part #6754-81-6210 or equivalent). After replacement, clear codes using diagnostic software and perform a test cycle to verify proper operation.

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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 consider professional assistance for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.