What is Komatsu PC240LC-10 Fault Code E-19?

Komatsu PC240LC-10 Fault Code E-19 indicates a hydraulic oil temperature sensor circuit malfunction or abnormal reading in the main hydraulic system. This code is triggered when the Engine Control Module (ECM) detects voltage values outside the normal operating range from the hydraulic oil temperature sensor, typically located in the hydraulic tank or main circuit.

This fault is critical for the PC240LC-10 because the hydraulic oil temperature directly affects system viscosity, component wear, and overall machine performance. When the ECM cannot accurately monitor hydraulic temperatures, it may initiate protective derate modes to prevent catastrophic damage to pumps, motors, and cylinder seals. In used excavators, this sensor circuit is particularly vulnerable due to years of vibration, heat cycling, and exposure to contaminated hydraulic fluid.

Common Symptoms

• Hydraulic oil temperature warning light illuminated on the instrument cluster, even when oil feels cool to touch
• Reduced engine power or hydraulic flow as the ECM enters protective mode assuming overheating
• Intermittent fault code activation that appears and disappears with machine vibration or temperature changes
• Abnormal temperature readings on the monitor display (showing extremely high or low values like -40°C or 150°C)
• Complete loss of temperature display functionality on the operator panel

Potential Causes

The most common causes for E-19 on used PC240LC-10 excavators include:

• Faulty hydraulic oil temperature sensor due to internal element degradation or contamination buildup (common after 6,000+ operating hours)
• Damaged or corroded wiring harness at connector points, especially where the harness routes near the hydraulic tank or frame (known rub point on this model)
• Loose or oxidized electrical connections at the sensor plug or ECM terminals caused by moisture intrusion
• Shorted or open circuit in the sensor wire, particularly in the section running along the swing bearing (susceptible to pinching)
• Failed ECM temperature input circuit, though less common than sensor/wiring issues
• Contaminated hydraulic oil causing sensor element fouling or coating

How to Troubleshoot and Fix Code E-19

Step 1: Visual Inspection and Connector Check Begin by locating the hydraulic oil temperature sensor (typically mounted in the hydraulic tank side panel). Inspect the wiring harness for obvious damage, chafing, or oil contamination. On used PC240LC-10s, carefully check where the harness passes near the swing motor and along the tank mounting bracket—these are known wear points. Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture. Clean with electrical contact cleaner if oxidation is present.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the sensor's resistance. With the sensor disconnected, check resistance across the sensor terminals. For the PC240LC-10, typical resistance should range between 200-5,000 ohms depending on oil temperature (consult your service manual for exact specifications). Compare readings at cold versus warm temperatures. If resistance is infinite (open circuit) or zero ohms (short circuit), replace the sensor.

Step 3: Circuit Voltage and Continuity Testing With the ignition on and sensor disconnected, measure reference voltage at the harness connector from the ECM—should read approximately 5 volts. Check continuity from the sensor connector back to the ECM pins using wiring diagrams. Pay special attention to ground circuits; corroded grounds are extremely common in used machines. If voltage is absent or continuity fails, trace and repair the harness wiring.

Step 4: Hydraulic Oil and Sensor Mounting Inspection For used excavators, verify the hydraulic oil condition. Severely contaminated or varnished oil can coat the sensor element, causing false readings. Check the sensor's physical mounting—vibration can loosen the sensor or crack its housing, allowing oil intrusion into electrical components. Replace damaged sensors and address oil contamination through filtration or fluid change.

Step 5: ECM Diagnostic Software Verification Connect Komatsu diagnostic software (KOMTRAX or service laptop) to monitor live sensor data. Observe temperature readings during warm-up cycles. If readings fluctuate wildly or remain static despite temperature changes, this confirms sensor failure. Clear codes after repairs and perform a functional test under load.

Disclaimer: This guide provides general troubleshooting procedures for Komatsu PC240LC-10 Code E-19. Hydraulic and electrical system repairs should be performed by qualified technicians following manufacturer service procedures. Always consult the official Komatsu service manual and use proper diagnostic tools. Improper repairs may result in equipment damage or safety hazards.