What is Komatsu PC210-10 Fault Code CA2357?

Fault Code CA2357 indicates a malfunction in the engine exhaust temperature sensor circuit within the Komatsu PC210-10's electronic control system. This Diagnostic Trouble Code (DTC) specifically signals that the Engine Control Module (ECM) has detected an abnormal voltage reading from the exhaust gas temperature (EGT) sensor, which monitors temperatures in the diesel particulate filter (DPF) regeneration system.

The EGT sensor is critical for the PC210-10's emissions control performance. It provides real-time data to the ECM to manage DPF regeneration cycles, preventing overheating and ensuring compliance with emission standards. When this sensor circuit fails, the machine cannot properly regulate exhaust temperatures, potentially leading to incomplete regeneration cycles, reduced engine performance, and accelerated component wear in the aftertreatment system.

Common Symptoms

When Code CA2357 is active on your Komatsu PC210-10, you may experience:

• Engine warning light or DPF indicator illuminated on the instrument cluster
• Engine derate mode activating, limiting power output to 70-80% of normal capacity
• Frequent or failed DPF regeneration attempts, causing excessive fuel consumption
• Black smoke emissions during operation due to incomplete combustion management
• Error messages on the monitor panel specifically referencing exhaust or DPF system issues

Potential Causes

The most common technical reasons for Code CA2357 on used PC210-10 excavators include:

• Failed EGT sensor element due to thermal stress or carbon buildup from extended operating hours
• Damaged or corroded wiring harness at the sensor connector, particularly where the harness routes near the turbocharger or exhaust manifold (known wear point on this model)
• Broken or frayed wiring caused by vibration or heat exposure in the engine compartment
• Poor ground connections at the sensor mounting point due to rust or loose hardware
• ECM internal fault (less common) affecting the sensor input circuit
• Moisture infiltration in connectors from failed seals, especially in machines operated in wet conditions

How to Troubleshoot and Fix Code CA2357

Step 1: Visual Inspection Begin by accessing the exhaust temperature sensor located in the DPF housing assembly. Inspect the wiring harness for obvious damage, including burnt insulation, chafing against metal edges, or oil contamination. On used excavators, pay special attention to harness routing near heat sources where insulation degradation is common. Check the sensor connector for corrosion, bent pins, or moisture—clean with electrical contact cleaner if necessary.

Step 2: Electrical Testing Using a digital multimeter, disconnect the EGT sensor connector and measure resistance across the sensor terminals. The typical resistance range for a functional sensor at ambient temperature should be 50-150 ohms (consult your PC210-10 service manual for exact specifications). Next, check for continuity between the sensor signal wire and the ECM connector—any reading above 5 ohms indicates wiring issues. Measure voltage supply from the ECM side; you should see approximately 5 volts with the key on, engine off.

Step 3: Component Replacement and Verification If resistance readings are out of specification or the sensor shows open or short circuit conditions, replace the EGT sensor with a genuine Komatsu OEM part (part number specific to PC210-10). After replacement, clear the fault code using Komatsu diagnostic software (KOMTRAX) or a compatible J1939 scan tool. Perform a stationary DPF regeneration to verify the new sensor provides accurate readings. For used machines, inspect the DPF mounting bolts and exhaust gaskets during sensor replacement, as exhaust leaks can cause premature sensor failure.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC210-10 service manual and consider engaging a certified Komatsu technician for complex diagnostics, especially when dealing with emissions-related components that may affect warranty or regulatory compliance.