Komatsu PC240LC-10 Fault Code CA697: Complete Diagnostic Guide

What is Komatsu PC240LC-10 Fault Code CA697?

Fault Code CA697 indicates a malfunction in the exhaust gas temperature sensor circuit, specifically detecting an abnormal voltage signal from the EGT sensor located in the aftertreatment system. This code is triggered when the engine control module (ECM) receives readings outside the predetermined voltage range from the diesel particulate filter (DPF) temperature monitoring circuit.

This fault is critical for the PC240LC-10's emission control performance because the ECM relies on accurate exhaust temperature data to manage DPF regeneration cycles and protect aftertreatment components from thermal damage. When CA697 appears, the machine may enter derate mode to prevent potential damage to the expensive DPF system, significantly impacting job site productivity.

Common Symptoms

When fault code CA697 is active, operators typically experience:

• Check engine light or malfunction indicator lamp illuminated on the monitor panel
• Automatic DPF regeneration failure or inability to initiate manual regeneration
• Engine power derate reducing hydraulic response and digging force by 20-40%
• Excessive black smoke during operation indicating incomplete combustion
• Warning messages on the LCD display specifically referencing exhaust system issues

Potential Causes

The most common technical reasons for CA697 on used PC240LC-10 excavators include:

• EGT sensor failure due to thermal stress or carbon buildup after 3,000-5,000 operating hours
• Wiring harness damage at known rub points near the turbocharger heat shield or DPF mounting brackets
• Corroded connectors in the sensor circuit, particularly where moisture enters through compromised sealing boots
• ECM calibration drift in older machines requiring software updates or module replacement
• Intermittent short circuits caused by damaged wire insulation rubbing against exhaust components

How to Troubleshoot and Fix Code CA697

Step 1: Visual Inspection Begin by inspecting the exhaust gas temperature sensor located downstream of the turbocharger. Check for physical damage, excessive carbon deposits, or broken wiring. On used excavators, carefully examine the wiring harness for abrasion marks where it routes near moving parts or hot surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the EGT sensor connector and measure resistance across the sensor terminals. Reference the Komatsu service manual for specific resistance values at ambient temperature (typically 80-120 ohms at 68°F). Check for voltage supply at the harness connector—should read approximately 5 volts with ignition on.

Step 3: Connector and Harness Verification Inspect connector pins for corrosion or bent terminals. On used machines, moisture intrusion is common. Clean connectors with electrical contact cleaner and apply dielectric grease. Perform a wiggle test while monitoring live data with Komatsu diagnostic software (KOMTRAX) to detect intermittent faults.

Step 4: Component Replacement If sensor readings are out of specification, replace the EGT sensor with a genuine Komatsu part. For persistent codes after sensor replacement, inspect ECM ground connections and verify harness continuity using an ohmmeter between sensor location and ECM pins.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC240LC-10 service manual and consider professional technician assistance for complex electrical diagnostics or if you lack proper diagnostic equipment.