Komatsu PC650LC-8R Fault Code E-32: Complete Diagnostic Guide

What is Komatsu PC650LC-8R Fault Code E-32?

Fault Code E-32 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 coolant temperature sensor sending irregular voltage signals outside the manufacturer's specified parameters, typically between 0.5-4.5 volts.

For the Komatsu PC650LC-8R's SAA6D140E-6 engine, accurate coolant temperature monitoring is critical for proper fuel injection timing, engine protection systems, and hydraulic oil temperature management. When this sensor fails, the ECM cannot properly regulate engine performance, potentially leading to overheating, reduced power output, or unnecessary engine derating that impacts productivity on the jobsite.

Common Symptoms

When Code E-32 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Engine derate mode activated, limiting maximum RPM to protect components
• Difficulty starting in cold conditions or extended cranking time
• Cooling fan running continuously at high speed regardless of actual temperature
• Inaccurate temperature gauge readings showing extreme high or low values (often pegged at maximum or minimum)

Potential Causes

The most common technical causes for E-32 on used PC650LC-8R excavators include:

• Coolant temperature sensor failure due to age-related degradation or internal short/open circuit
• Damaged or corroded wiring harness connections at the sensor plug (common wear point near engine block)
• Chafed wires along the harness routing path between sensor and ECM, particularly where harness contacts frame rails
• Corroded or loose ground connections affecting sensor circuit integrity
• Contaminated coolant causing sensor element fouling or deposits
• ECM internal fault (rare, but possible in high-hour machines)
• Aftermarket sensor installation with incorrect resistance specifications

How to Troubleshoot and Fix Code E-32

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block's coolant passage. Check the connector for corrosion, bent pins, or moisture intrusion. On used excavators, examine the entire wiring harness from sensor to ECM for chafing, especially at known rub points near engine mounts and frame crossmembers.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across its terminals. At 68°F (20°C), resistance should typically read 2,000-3,000 ohms (consult Komatsu service manual for exact specifications). Test harness continuity from sensor connector to ECM pins, checking for opens or shorts to ground.

Step 3: Voltage Signal Check With ignition on and sensor connected, backprobe the signal wire at the sensor connector. You should read approximately 5 volts reference voltage from the ECM. A cold engine should show 3-4 volts, dropping to 0.5-1.5 volts at operating temperature.

Step 4: Component Replacement If sensor resistance is out of specification or harness shows damage, replace the faulty component using genuine Komatsu parts. For used machines, always apply dielectric grease to connector pins to prevent future corrosion. Clear codes using Komatsu diagnostic software (KOMTRAX) or compatible scan tool and verify repair with a test run.

---

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