What is Komatsu PC210-7 Fault Code E201?

Fault Code E201 on the Komatsu PC210-7 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the engine control module (ECM). This code is generated when the ECM receives signals outside the expected voltage range from the coolant temperature sensor, which monitors the engine's operating temperature to optimize fuel injection, idle speed, and prevent overheating.

This fault is critical for the PC210-7's performance because the Komatsu SAA6D107E-1 engine relies heavily on precise temperature data to adjust combustion parameters. When the ECM cannot accurately determine coolant temperature, it may default to safe-mode operation, reducing engine power and efficiency. For used excavators, this code often surfaces due to sensor degradation or wiring issues common in machines with high operating hours.

Common Symptoms

• Engine warning lamp illuminated on the instrument cluster, often accompanied by a temperature gauge reading abnormally high or low
• Reduced engine power or derate mode activation, limiting hydraulic performance during digging and lifting operations
• Hard starting or rough idle, particularly noticeable during cold starts when temperature compensation is critical
• ECM error logging visible through Komatsu diagnostic software (KOMTRAX or PC-based tools)
• Intermittent code triggering, especially on used machines where connector corrosion causes sporadic signal interruptions

Potential Causes

• Faulty coolant temperature sensor (common failure point after 8,000+ operating hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at known rub points near the engine block and frame rail
• Loose or oxidized electrical connectors at the sensor or ECM interface, typical in machines exposed to dusty or wet conditions
• ECM internal fault (rare, but possible in older units or those exposed to voltage spikes)
• Coolant system issues such as air pockets or actual overheating causing legitimate sensor readings that trigger the code
• Aftermarket sensor installation with incorrect resistance specifications for the Komatsu system

How to Troubleshoot and Fix Code E201

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for physical damage, coolant leaks around the sensor base, and corrosion on the electrical connector. On used excavators, examine the wiring harness for abrasion points where it contacts metal surfaces—a common failure location on the PC210-7.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance. At 20°C (68°F), the sensor should read approximately 2,000-3,000 ohms (consult your service manual for exact specs). Also check wiring continuity from the sensor connector to the ECM—resistance should be less than 5 ohms. Measure voltage supply from the ECM with the key on: expect around 5 volts reference voltage.

Step 3: Component Replacement and Verification If resistance or voltage values fall outside specifications, replace the coolant temperature sensor with a genuine Komatsu part (Part #6732-81-3210 or equivalent). Before installation, clean connector terminals with electrical contact cleaner and apply dielectric grease. For used machines with over 10,000 hours, consider replacing the sensor-to-ECM harness section if insulation shows cracking. Clear codes using Komatsu diagnostic software and perform a test run under load.

Disclaimer: While this guide provides technical troubleshooting steps, complex electrical diagnostics should be performed by certified Komatsu technicians with proper diagnostic equipment. Always consult the PC210-7 service manual and prioritize safety when working on pressurized cooling systems.