Komatsu PC220-10 Fault Code E-36: Complete Diagnostic Guide

What is Komatsu PC220-10 Fault Code E-36?

Fault Code E-36 on the Komatsu PC220-10 indicates a malfunction in the engine coolant temperature sensor circuit, specifically detecting an abnormal voltage signal or open/short circuit condition in the ECT (Engine Coolant Temperature) sensor system. This code is triggered when the ECM (Engine Control Module) receives sensor readings outside the normal operating range of 0.5-4.5 volts, suggesting the sensor cannot accurately monitor engine temperature.

This fault is critical for the PC220-10's performance because the coolant temperature sensor directly influences fuel injection timing, idle speed control, and the diesel particulate filter (DPF) regeneration cycle. The Komatsu SAA6D107E-1 engine relies on precise temperature data to optimize combustion efficiency and prevent overheating. Ignoring this code can lead to poor fuel economy, failed emissions systems, and potential engine damage on used machines with accumulated operating hours.

Common Symptoms

• Engine warning lamp illuminated on the monitor panel with E-36 displayed
• Hard starting or rough idle, especially during cold starts when ECM defaults to preset temperature values
• Excessive white or black smoke from exhaust due to incorrect fuel mixture adjustments
• Radiator fan running continuously at high speed regardless of actual engine temperature
• Reduced engine power or derate mode activation to protect the engine from potential overheating

Potential Causes

On used PC220-10 excavators, this fault typically stems from sensor degradation after 5,000+ operating hours, where internal resistance values drift outside specifications. Wiring harness chafing is common near the thermostat housing where the harness contacts the engine block during vibration—a known wear point on Komatsu dash-10 series machines.

Corroded connector terminals at the three-pin ECT sensor plug frequently cause intermittent signals, especially on machines operated in coastal or high-humidity environments. Coolant contamination entering the sensor through a failing O-ring seal can short the internal circuitry. Less commonly, ECM internal faults in the temperature input channel occur, though this is rare compared to sensor/wiring issues.

How to Troubleshoot and Fix Code E-36

Step 1: Visual Inspection Locate the coolant temperature sensor on the thermostat housing (left side of engine block). Inspect the wiring harness for obvious damage, melting, or worn insulation where it contacts metal surfaces. Check the connector for green corrosion, bent pins, or moisture intrusion—common on used machines. Clean connections with electrical contact cleaner and dielectric grease.

Step 2: Sensor Resistance Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across sensor terminals. At 20°C (68°F), resistance should read approximately 2,200-2,800 ohms; at 80°C (176°F), it should drop to 280-350 ohms. Values outside this range confirm sensor failure requiring replacement (Komatsu part #6754-81-9120).

Step 3: Wiring Harness Verification With the sensor disconnected, check continuity between each harness wire and the ECM connector (pins vary by serial number—consult service manual). Resistance should be less than 1 ohm for signal and ground wires. Also check for short circuits to ground (should read infinite resistance). Pay special attention to harness sections near engine mounts where vibration causes wire fatigue in older excavators.

Step 4: ECM Signal Testing Using Komatsu KONTROL diagnostic software or compatible scan tool, monitor live ECT sensor voltage with engine at operating temperature. Normal voltage ranges 0.5-0.8V at 80°C. Erratic readings or values stuck at 5V (open circuit) or 0V (short circuit) confirm wiring/sensor issues if previous tests passed.

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Disclaimer: This guide provides general diagnostic procedures for experienced technicians. Always consult the official Komatsu PC220-10 service manual for torque specifications, pin-out diagrams, and safety procedures specific to your machine's serial number. If unfamiliar with electrical diagnostics, consult a certified Komatsu technician to prevent damage to ECM systems.