What is Komatsu PC210LC-8 Fault Code E15 CA435?

Fault Code E15 CA435 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 generated when the engine control module (ECM) receives voltage readings outside the acceptable range from the coolant temperature sensor (CTS), typically located on the engine block or cylinder head.

For the Komatsu PC210LC-8 excavator equipped with the SAA6D107E-1 engine, accurate coolant temperature monitoring is critical for proper fuel injection timing, engine protection, and emission control. When this sensor circuit fails, the ECM cannot properly manage engine operating parameters, potentially leading to reduced performance and increased wear on internal components.

Common Symptoms

• Warning lamp illuminated on the instrument cluster with E15 displayed on the monitor panel
• Engine running in derate mode with reduced power output and limited RPM range
• Difficulty starting in cold conditions or prolonged cranking before engine fires
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Inaccurate temperature gauge readings showing extremely high or low readings that don't match actual operating conditions

Potential Causes

The most common technical causes for Code E15 CA435 on used PC210LC-8 excavators include:

• Coolant temperature sensor failure due to internal element deterioration or moisture ingress after years of thermal cycling
• Damaged or corroded wiring harness connections at the sensor connector, particularly where the harness routes near hot exhaust components
• Open circuit in the sensor signal wire caused by harness chafing against frame members or hydraulic lines—a known wear point on this model near the fuel filter housing
• Corroded or backed-out pins in the ECM connector (X2 connector, typically pin 23 for signal and pin 46 for ground)
• Failed ECM internal circuit, though significantly less common than sensor or wiring issues

How to Troubleshoot and Fix Code E15 CA435

Step 1: Visual Inspection Begin with a thorough inspection of the coolant temperature sensor and its connector located on the engine's water outlet housing. On used excavators, check for coolant leaks, corrosion, or physical damage. Disconnect the sensor connector and inspect pins for corrosion, bent terminals, or moisture contamination—common issues after 5,000+ operating hours.

Step 2: Sensor Resistance Testing Using a digital multimeter, measure the resistance across the sensor terminals with the sensor removed from the engine. At 68°F (20°C), resistance should read approximately 2,200-2,700 ohms. At 176°F (80°C), it should drop to 280-330 ohms. Values outside this range indicate sensor replacement is necessary (Komatsu part number 22U-06-22360).

Step 3: Circuit Voltage and Continuity Checks With the sensor disconnected and ignition on, measure voltage at the harness connector. You should see approximately 5 volts on the signal wire. Check continuity between the sensor ground wire and chassis ground—resistance should be less than 1 ohm. Inspect the harness routing near the turbocharger and exhaust manifold where heat damage and abrasion commonly occur on older machines.

Step 4: ECM Connection Verification Trace wiring back to the ECM connector and verify secure connection with no backed-out terminals. For used excavators with previous electrical work, verify no aftermarket splices or repairs exist that could introduce high resistance. Use Komatsu's KOMTRAX Plus diagnostic software to monitor live sensor data and verify the ECM is receiving proper signals after repairs.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu service manual for your specific machine serial number, and consider professional diagnostic services for complex electrical issues or if you lack proper testing equipment.