Komatsu PC220-10 Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC220-10 Fault Code E-17?

Komatsu PC220-10 Fault Code E-17 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 specifically relates to the temperature monitoring system that protects the engine from overheating damage.

The E-17 code triggers when the ECM detects voltage signals outside the normal operating range (typically 0.5-4.5V) from the coolant temperature sensor, or when readings indicate physically impossible temperature values. For the PC220-10's SAA6D107E-1 engine, accurate coolant temperature monitoring is critical for proper fuel injection timing, emission control, and preventing catastrophic engine damage. This fault can put the machine into derate mode, significantly reducing productivity on job sites.

Common Symptoms

When fault code E-17 is active, operators typically experience:

• Warning light illumination on the instrument cluster with possible audible alarm
• Engine derate or reduced power output to prevent potential overheating damage
• Erratic temperature gauge readings that fluctuate abnormally or show maximum/minimum values regardless of actual engine temperature
• Hard starting conditions or rough idle, particularly when the engine is cold
• Increased fuel consumption due to incorrect fuel mapping based on faulty temperature data

Potential Causes

The most common technical causes for E-17 on used PC220-10 excavators include:

• Faulty coolant temperature sensor (thermal element degradation common after 5,000+ hours)
• Damaged or corroded wiring harness connections at the sensor connector, particularly where the harness routes near the exhaust manifold
• Shorted or open circuit in the sensor wiring due to harness chafing against engine components
• Corroded ECM connector pins (especially on machines exposed to harsh environments)
• Low coolant level causing sensor exposure to air instead of coolant
• Failed ECM (rare, but possible on high-hour used machines)

How to Troubleshoot and Fix Code E-17

Step 1: Visual Inspection Begin by checking coolant level in the radiator and overflow tank. Inspect the sensor connector (located on the engine block near the thermostat housing) for corrosion, moisture, or damaged pins. Examine the wiring harness for visible damage, particularly where it contacts hot engine surfaces or sharp edges.

Step 2: Sensor Resistance Testing Disconnect the coolant temperature sensor connector. Using a digital multimeter, measure resistance across the sensor terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. At operating temperature (176°F/80°C), it should drop to roughly 300-400 ohms. Values significantly outside this range indicate sensor failure.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition on (engine off), measure voltage at the harness connector. You should see approximately 5 volts on the signal wire from the ECM. No voltage indicates a wiring issue or ECM problem.

Step 4: Harness Continuity Testing Test for continuity between the sensor connector and ECM pins using the PC220-10 wiring diagram. Check for short circuits to ground or power. On used excavators, pay special attention to harness sections that show heat discoloration or wear marks.

Step 5: Component Replacement Replace the sensor using genuine Komatsu parts (part #6738-81-7130 or equivalent). Ensure proper torque specifications and apply dielectric grease to connections. Clear codes using Komatsu diagnostic software (KOMTRAX) and verify repair with a test run.

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