Komatsu PC210-10 Fault Code CA1695: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code CA1695?

Fault Code CA1695 indicates a malfunction in the Engine Water Temperature Sensor Circuit, specifically detecting an abnormal voltage signal or circuit irregularity in the coolant temperature monitoring system. This code is triggered when the Electronic Control Module (ECM) receives voltage readings outside the acceptable range from the engine coolant temperature sensor, typically above 4.8V or below 0.2V.

This sensor is critical for the PC210-10's performance because it directly influences fuel injection timing, combustion efficiency, and engine protection protocols. When the ECM cannot accurately measure coolant temperature, it may default to a fail-safe mode, resulting in reduced engine power and increased fuel consumption. For this Komatsu model using the SAA6D107E-3 engine, precise temperature monitoring ensures optimal hydraulic pump performance and prevents catastrophic overheating.

Common Symptoms

When CA1695 is active on your PC210-10, operators typically experience:

• Engine warning light illuminated on the monitor panel with fault code displayed
• Reduced engine power (derate mode) limiting digging force and travel speed
• Poor cold-start performance or rough idling during warm-up
• Cooling fan running continuously at maximum speed regardless of actual temperature
• Inaccurate temperature gauge readings showing extreme high or low values inconsistently

Potential Causes

The most common technical reasons for CA1695 appearing on used PC210-10 excavators include:

• Failed coolant temperature sensor due to internal resistance drift (common after 8,000+ operating hours)
• Damaged sensor wiring harness caused by rubbing against the engine block near the thermostat housing—a known wear point on this model
• Corroded or loose connector pins at the sensor plug, especially on machines operating in high-moisture environments
• Short circuit to ground in the sensor signal wire between the sensor and ECM
• ECM internal fault affecting the 5V reference voltage supply circuit (rare but possible in older units)

How to Troubleshoot and Fix Code CA1695

Step 1: Visual Inspection Begin by locating the engine coolant temperature sensor on the thermostat housing (right side of engine block). Inspect the sensor connector for corrosion, bent pins, or moisture intrusion. On used excavators, check for wire harness chafing where the loom passes near engine mounts—this is a high-wear area on PC210 models.

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 2,400-2,700 ohms. If readings are infinite (open circuit) or near zero (shorted), replace the sensor. Next, check the harness by measuring voltage at the connector with ignition on—you should see approximately 5V reference voltage from the ECM.

Step 3: Signal Circuit Verification With the sensor disconnected and ignition on, use your multimeter to check for continuity between the signal wire and ground—there should be no continuity (infinite resistance). If continuity exists, trace the harness to locate the short circuit. For used machines, pay special attention to areas where protective loom covering has deteriorated.

Step 4: Advanced Diagnostics Connect Komatsu KOMTRAX diagnostic software or a compatible scan tool to monitor live sensor data. Observe temperature readings while the engine warms up—values should rise smoothly from ambient to operating temperature (82-95°C). Erratic jumps or frozen readings indicate sensor or wiring issues.

Critical for Used Equipment: Before replacing components, thoroughly clean all connectors with electrical contact cleaner and apply dielectric grease to prevent future corrosion. Inspect rubber grommets and harness protective coverings, as deterioration allows moisture penetration in aging machines.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC210-10 service manual and consider professional diagnostic services for complex electrical issues. Improper troubleshooting may cause additional system damage or void warranties.