What is Komatsu PC220-7 Fault Code E116?

Fault Code E116 on the Komatsu PC220-7 indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage signal from the coolant temperature sensor, typically indicating an open circuit, short circuit, or sensor reading outside the acceptable range (usually -40°C to 150°C).

The ECT sensor is critical for the PC220-7's Komatsu SAA6D107E-1 engine because it directly influences fuel injection timing, idle speed control, and engine warm-up procedures. When this sensor fails or provides inaccurate data, the ECM enters a failsafe mode using default temperature values, which can significantly reduce engine efficiency and potentially cause long-term damage if the engine overheats undetected.

Common Symptoms

When Code E116 is active on your PC220-7, operators typically experience:

• Check Engine Warning Light illuminated on the instrument cluster, often accompanied by audible warning beeps
• Hard starting conditions, especially during cold weather, due to incorrect fuel delivery calculations
• Rough idle or fluctuating RPM as the ECM struggles to compensate for missing temperature data
• Reduced engine power or derate mode activation to prevent potential overheating damage
• Cooling fan running continuously at high speed, regardless of actual engine temperature

Potential Causes

The most common technical reasons for E116 on used PC220-7 excavators include:

• Failed ECT sensor due to age-related internal element degradation (common after 8,000+ operating hours)
• Damaged wiring harness near the engine block where heat and vibration cause insulation breakdown, particularly at harness routing points behind the fuel filter
• Corroded or loose electrical connectors at the sensor or ECM pins, especially on machines exposed to high-moisture environments
• Coolant contamination on sensor terminals causing erratic resistance readings
• ECM internal fault (rare, but possible on older machines with 12,000+ hours)

How to Troubleshoot and Fix Code E116

Step 1: Visual Inspection Begin by locating the ECT sensor on the left side of the engine block near the thermostat housing. Inspect the wiring harness for obvious damage, chafing against the engine block, or melted insulation. Check the two-pin connector for corrosion, bent pins, or coolant intrusion—common on used machines.

Step 2: Sensor Resistance Testing Disconnect the sensor connector and use a digital multimeter set to resistance (Ω) mode. At 20°C (68°F), the sensor should read approximately 2,450 ohms; at 80°C (176°F), approximately 290-330 ohms. Values significantly outside these ranges indicate sensor replacement is necessary (Komatsu Part #6754-61-6210).

Step 3: Circuit Voltage Check With the ignition on and sensor disconnected, check for 5V reference voltage at the harness connector from the ECM. Also verify proper ground continuity (less than 1 ohm resistance to chassis ground). If voltage is absent or ground circuit shows high resistance, trace the harness back to the ECM, checking for breaks or corrosion at intermediate connectors—a prevalent issue in excavators with 10+ years of service.

Step 4: Verify Repair After replacing faulty components, clear codes using Komatsu KOMTRAX diagnostic software or a compatible scan tool, then run the engine through heat cycles to confirm the code doesn't return.

Disclaimer: This guide provides general diagnostic procedures. For used excavators with complex electrical issues or persistent codes, consult a certified Komatsu technician or authorized service center to prevent misdiagnosis and unnecessary parts replacement.