Komatsu PC210-10 Fault Code CA144: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code CA144?

Fault Code CA144 on the Komatsu PC210-10 excavator indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormal voltage signal or open circuit condition in the coolant temperature monitoring system. This code is logged by the Engine Control Module (ECM) when it receives voltage readings outside the acceptable range from the coolant temperature sensor (typically 0.2-4.8V depending on temperature).

The coolant temperature sensor is critical for the PC210-10's SAA6D107E-1 engine performance because the ECM uses this data to adjust fuel injection timing, optimize combustion efficiency, and protect the engine from overheating. When this sensor fails or provides unreliable data, the engine may operate in a reduced performance mode or experience poor fuel economy and increased emissions.

Common Symptoms

When Code CA144 is active on your Komatsu PC210-10, you may experience:

• Check Engine Light or warning indicator illuminated on the monitor panel
• Engine derate mode activated, limiting maximum RPM and reducing hydraulic performance
• Difficulty starting the engine, particularly in cold weather conditions
• Engine running rich (black smoke) or lean due to incorrect fuel-air mixture calculations
• Coolant temperature gauge reading incorrectly or displaying maximum temperature immediately upon startup

Potential Causes

The most common technical reasons for CA144 on used PC210-10 excavators include:

• Faulty coolant temperature sensor – internal resistance degradation common after 5,000+ operating hours
• Damaged wiring harness – wire chafing near the thermostat housing where the harness runs close to exhaust components
• Corroded or loose connector pins at the sensor plug (P106 connector) due to coolant seepage or environmental exposure
• Open circuit in the signal wire between the sensor and ECM (typically a brown wire on this model)
• ECM internal fault (rare) – corrupted temperature input circuit on the control module
• Improper sensor installation after maintenance, causing poor thermal contact or cross-threading

How to Troubleshoot and Fix Code CA144

Step 1: Visual Inspection Begin by locating the coolant temperature sensor on the engine block near the thermostat housing (driver's side of engine). Inspect the wiring harness for obvious damage, rubbing against metal surfaces, or heat damage. Check the connector for corrosion, bent pins, or coolant contamination—common in used excavators operating in wet conditions.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. At room temperature (20°C/68°F), resistance should read approximately 2,000-3,000 ohms. Compare readings to Komatsu's specifications. Next, check for continuity in the signal wire from the sensor connector back to ECM pin (consult wiring diagram for exact terminal). Resistance should be less than 5 ohms.

Step 3: Voltage Supply Check With the ignition on and sensor disconnected, measure voltage at the harness connector. You should see approximately 5V reference voltage from the ECM. If voltage is absent, trace the circuit for breaks or check ECM power supply.

Step 4: Component Replacement If the sensor tests faulty, replace it with a genuine Komatsu part (Part #6261-81-6910 or equivalent). For used excavators, always apply fresh anti-seize compound to threads and ensure proper torque (typically 15-20 ft-lbs). Replace the connector if pins show any corrosion.

Step 5: Clear Code and Verify After repairs, use Komatsu diagnostic software (KOMTRAX) or a compatible diagnostic tool to clear the fault code. Run the engine through temperature cycles and monitor for code recurrence.

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Disclaimer: This guide provides general diagnostic information. Always consult the Komatsu PC210-10 service manual and consider professional assistance from certified Komatsu technicians for complex electrical diagnostics or if you're unfamiliar with high-voltage systems.