What is Komatsu PC210LC-10 Fault Code DW43KA?

Fault Code DW43KA indicates a malfunction in the hydraulic oil temperature sensor circuit, specifically detecting an abnormal voltage signal being sent to the Engine Control Module (ECM). This code triggers when the ECM receives readings outside the expected range from the hydraulic oil temperature sensor, which monitors the operating temperature of the hydraulic system fluid.

For the Komatsu PC210LC-10, this sensor is critical because it protects the hydraulic system from overheating damage and ensures optimal viscosity for hydraulic performance. The ECM uses this data to regulate engine RPM and activate warning systems when temperatures exceed safe thresholds. On used excavators, this code frequently appears due to sensor degradation, corroded connectors, or damaged wiring harnesses common in machines with extended operational hours.

Common Symptoms

• Hydraulic oil temperature warning light illuminates on the instrument cluster, often accompanied by an audible alarm
• Reduced hydraulic performance or sluggish cylinder response as the ECM enters a protective derate mode
• Intermittent code activation, especially during cold starts or after extended operation, indicating connection issues
• Engine RPM limitation to prevent potential hydraulic system damage from unmonitored temperature conditions
• Multiple related codes may appear simultaneously if the ECM detects conflicting sensor data

Potential Causes

The most common causes for DW43KA on used PC210LC-10 excavators include:

• Failed hydraulic oil temperature sensor due to internal resistance drift or complete circuit failure (typical after 8,000+ operating hours)
• Corroded or loose connector pins at the sensor harness connection point near the hydraulic tank
• Damaged wiring harness caused by rubbing against the frame or hydraulic lines, particularly where the harness routes along the left side of the main pump
• Contaminated sensor threads with metal debris or hydraulic fluid residue causing false readings
• ECM internal fault (rare) where the input circuit for temperature monitoring has failed
• Low voltage supply to the sensor circuit from battery or charging system issues

How to Troubleshoot and Fix Code DW43KA

Step 1: Visual Inspection and Connector Check Begin by locating the hydraulic oil temperature sensor on the hydraulic tank (typically mounted on the return line side). Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture. On used excavators, this connector often shows green corrosion from hydraulic mist exposure. Clean contacts with electrical contact cleaner and apply dielectric grease before reconnection.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the sensor resistance with the engine cold. A functional sensor typically reads between 2,000-3,000 ohms at 20°C (68°F). Compare your reading against Komatsu specifications in the service manual. If resistance is open circuit (infinite ohms) or short circuit (near zero ohms), replace the sensor.

Step 3: Wiring Harness Continuity Check With the sensor disconnected, test continuity from the sensor connector back to the ECM pins (refer to wiring diagram for specific pin locations). Check for shorts to ground by measuring resistance between each wire and chassis ground—it should read infinite resistance. Inspect the harness routing for wear points where it contacts frame members or hydraulic hoses.

Step 4: Voltage Supply Verification With ignition on and sensor disconnected, measure reference voltage at the sensor connector. The ECM should supply approximately 5 volts DC on the signal wire. If voltage is absent or incorrect, suspect ECM issues or a blown fuse in the sensor power circuit.

Step 5: Test with Known Good Sensor If available, temporarily install a new or known-good sensor to determine if the issue is component failure or wiring-related. Clear codes using Komatsu diagnostic software (KOMTRAX Plus) or a compatible diagnostic scanner and operate the machine to verify the fault doesn't return.

Used Equipment Consideration: On high-hour PC210LC-10 machines, always inspect the sensor mounting boss for thread damage and check that the O-ring seal isn't allowing air intrusion, which can cause erratic readings. Replace the sensor gasket during reinstallation to prevent future false codes.

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Disclaimer: This guide provides general troubleshooting information for educational purposes. Always consult the official Komatsu service manual for your specific machine serial number and seek assistance from certified Komatsu technicians for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.