Komatsu PC750-7 Fault Code E207: Complete Diagnostic Guide

What is Komatsu PC750-7 Fault Code E207?

Fault Code E207 on the Komatsu PC750-7 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 or detecting temperatures outside the normal operating parameters.

The coolant temperature sensor plays a critical role in the PC750-7's SAA6D140E-5 engine management system. It provides real-time data to the ECM for fuel injection timing, engine protection protocols, and hydraulic system temperature compensation. When this sensor fails or sends erratic signals, the machine cannot properly regulate engine performance, potentially leading to overheating, reduced power output, or unnecessary engine derating.

Common Symptoms

When Code E207 is active, operators typically experience:

• Engine warning light illuminated on the monitor panel with possible audible alarm
• Reduced engine power or automatic derate mode to prevent overheating damage
• Inaccurate coolant temperature readings displayed on the monitor (showing extremely high or low values)
• Difficulty starting in cold conditions due to improper fuel enrichment
• Hydraulic system sluggishness as the ECM compensates for perceived temperature issues

Potential Causes

The most common technical causes for E207 on used PC750-7 excavators include:

• Faulty coolant temperature sensor due to internal element degradation (common after 8,000+ operating hours)
• Damaged or corroded wiring harness at connector points, especially near the engine block where heat and vibration cause wear
• Corroded sensor connector pins from coolant leaks or moisture intrusion
• Open or short circuit in the sensor wiring between the sensor and ECM
• ECM internal fault (rare, but possible in high-hour machines)
• Low coolant level causing intermittent sensor exposure and erratic readings

How to Troubleshoot and Fix Code E207

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for coolant leaks, corrosion on the connector, and verify proper coolant level. On used excavators, examine the wiring harness for rub points against the engine block or frame—a common failure point on the PC750-7.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. At 20°C (68°F), resistance should typically read 2,000-3,000 ohms (consult your service manual for exact specifications). Check for continuity in the wiring harness from sensor to ECM connector. Measure voltage supply at the sensor connector with ignition on—should read approximately 5 volts.

Step 3: Component Replacement and Verification If resistance values are out of specification or wiring shows damage, replace the faulty component. For used machines, always apply dielectric grease to connector pins to prevent future corrosion. Clear the fault code using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool, then monitor for code recurrence during a full operating cycle.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional technician assistance for complex electrical diagnostics.