Komatsu PC800SE-7 Fault Code E201: Complete Diagnostic Guide

What is Komatsu PC800SE-7 Fault Code E201?

Fault Code E201 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 PC800SE-7's SAA6D170E-7 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 premature component wear in this 52-ton class excavator.

Common Symptoms

When Code E201 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Reduced engine power (derate mode) as the ECM enters fail-safe operation
• Erratic temperature gauge readings or gauge stuck at minimum/maximum positions
• Difficulty starting when the engine is cold, as the ECM cannot adjust fuel delivery properly
• Increased fuel consumption due to improper fuel mapping based on faulty temperature data

Potential Causes

The most common technical causes for E201 on used PC800SE-7 excavators include:

• Coolant temperature sensor failure due to age-related degradation or thermal cycling damage
• Wiring harness damage at known rub points near the engine block mounting brackets
• Corroded or loose connector pins at the sensor plug (3-pin connector), especially on machines operating in coastal or high-humidity environments
• ECM internal circuit failure (less common but possible on high-hour machines)
• Coolant contamination causing sensor element coating or failure
• Ground circuit issues affecting sensor reference voltage

How to Troubleshoot and Fix Code E201

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block's coolant passage. Check the wiring harness for abrasion, particularly where it routes near moving components or sharp edges. On used excavators, examine connector pins for corrosion, bent pins, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, measure sensor resistance. At 20°C (68°F), resistance should read approximately 2,000-3,000 ohms (consult service manual for exact specifications). Test supply voltage at the sensor connector with ignition on—expect approximately 5 volts. Check ground continuity between sensor ground and chassis ground (should be less than 1 ohm).

Step 3: Dynamic Testing With the engine cold, monitor sensor voltage using Komatsu KOMTRAX diagnostic software or compatible scan tool while warming the engine. Voltage should decrease smoothly as temperature rises. Erratic readings indicate sensor failure.

Step 4: Repair Actions For used machinery, clean all connector contacts with electrical contact cleaner before replacing components. If sensor tests faulty, replace with genuine Komatsu part (P/N 6261-81-6510 or equivalent). Repair any damaged harness sections with proper gauge wire and heat-shrink connections. Clear codes and verify repair with test cycle.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number. Complex electrical issues should be diagnosed by certified technicians with proper diagnostic equipment.