Komatsu PC200LC-7 Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC200LC-7 Fault Code E-17?

Fault Code E-17 on the Komatsu PC200LC-7 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal temperature reading detected by the Engine Control Module (ECM). This code specifically relates to the coolant temperature monitoring system that regulates engine protection protocols and cooling fan operation.

The coolant temperature sensor sends voltage signals to the ECM, allowing the controller to manage fuel injection timing, idle speed, and activate warning systems when temperatures exceed safe operating ranges. On the PC200LC-7's SAA6D102E-2 engine, this sensor is critical because prolonged operation with inaccurate temperature data can cause severe engine damage, including head gasket failure, cylinder scoring, or complete engine seizure. This fault compromises the machine's ability to protect itself from overheating conditions.

Common Symptoms

When Code E-17 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel, often accompanied by audible alarm
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Temperature gauge displaying erratic readings or stuck at maximum/minimum positions
• Engine derate or reduced power output as the ECM enters protective mode
• Difficulty starting when the engine is cold, as the ECM receives incorrect temperature data affecting fuel delivery

Potential Causes

The most common technical failures triggering E-17 on used PC200LC-7 excavators include:

• Coolant temperature sensor failure due to internal element degradation (common after 5,000+ operating hours)
• Wiring harness damage at the sensor connector or along the routing path near the turbocharger where heat and vibration cause insulation breakdown
• Corroded or loose connector pins at the sensor plug—a frequent issue on machines exposed to harsh environments
• ECM internal fault in the temperature monitoring circuit (less common but possible on high-hour machines)
• Broken or shorted sensor ground wire, particularly at ground terminal E17 on the engine block
• Coolant contamination causing sensor probe coating and inaccurate readings

How to Troubleshoot and Fix Code E-17

Step 1: Visual Inspection Locate the coolant temperature sensor on the thermostat housing of the SAA6D102E-2 engine. Inspect the sensor connector for corrosion, bent pins, or moisture intrusion. Check the wiring harness from sensor to ECM for chafing points, particularly where it passes near exhaust components or moving parts—this is a known wear point on used PC200LC-7 machines.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At 68°F (20°C), resistance should read approximately 2,450 ohms; at 176°F (80°C), approximately 300 ohms. Values outside this range indicate sensor failure. Next, check continuity on both sensor circuit wires from the connector back to the ECM pins to identify breaks or high-resistance connections.

Step 3: Signal Voltage Verification With ignition on and sensor connected, back-probe the signal wire at the connector. You should see approximately 4.8-5.0 volts with the engine cold, dropping as temperature increases. Constant 5V or 0V indicates circuit problems rather than sensor failure.

Step 4: Component Replacement and Verification If diagnostics confirm sensor failure, replace with a genuine Komatsu part (6732-81-3110) to ensure proper calibration. For used excavators, always apply dielectric grease to connector pins to prevent future corrosion. After replacement, clear codes using Komatsu diagnostic software (KOMTRAX or PC-based tools) and monitor temperature readings during a complete warm-up cycle to confirm proper operation.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and seek qualified professional assistance for complex electrical diagnostics or major repairs.