Komatsu PC110-8M0 Fault Code E-35: Complete Diagnostic Guide

What is Komatsu PC110-8M0 Fault Code E-35?

Fault Code E-35 on the Komatsu PC110-8M0 indicates a malfunction in the engine control system, specifically related to abnormal voltage output from the engine speed sensor circuit. This code is triggered when the ECM (Engine Control Module) detects irregular signals from the speed sensor that monitors crankshaft or camshaft rotation.

The engine speed sensor is critical for proper fuel injection timing, engine performance, and overall machine operation on this compact excavator model. When this sensor circuit fails or sends erratic signals, the ECM cannot accurately calculate engine RPM, leading to performance degradation or complete shutdown. For the PC110-8M0's 4-cylinder diesel engine, maintaining accurate speed readings is essential for optimal hydraulic pump control and load management during excavation work.

Common Symptoms

When Code E-35 is active on your Komatsu PC110-8M0, operators typically experience:

• Engine warning light illuminated on the instrument panel, often accompanied by audible alarm
• Erratic engine RPM fluctuations or sudden drops in power during operation
• Difficulty starting the engine, or engine stalling immediately after startup
• Reduced hydraulic performance due to inconsistent engine speed affecting pump output
• Derate mode activation, limiting engine power to protect internal components

Potential Causes

For used Komatsu PC110-8M0 excavators, Code E-35 commonly results from:

• Worn or damaged speed sensor, particularly on machines with high operating hours (sensor failure rate increases after 5,000+ hours)
• Corroded or loose wiring connections at the sensor harness connector—common in machines exposed to mud and moisture
• Harness chafing along the engine block where vibration causes wire insulation breakdown
• Faulty ECM (less common, but possible in older units with electrical system stress)
• Damaged sensor reluctor ring or flywheel teeth causing irregular magnetic field readings
• Low supply voltage to the sensor due to poor ground connections or battery issues

How to Troubleshoot and Fix Code E-35

Step 1: Visual Inspection Begin by locating the engine speed sensor mounted on the engine block near the flywheel housing. Inspect the sensor connector for corrosion, moisture intrusion, or bent pins. On used excavators, check for oil contamination around the sensor mounting area. Clean all connections with electrical contact cleaner.

Step 2: Electrical Testing Using a digital multimeter, check the sensor's resistance. The Komatsu speed sensor should typically read between 150-300 ohms (consult your service manual for exact specifications). Test supply voltage at the connector—you should see approximately 8-12 volts DC with the ignition on. Check ground continuity from the sensor body to battery negative.

Step 3: Harness Inspection Trace the wiring harness from the sensor to the ECM, looking for wear points where the harness contacts the engine or frame. Common rub points on the PC110-8M0 include areas near the engine mount brackets and fuel filter housing. Repair any damaged insulation with proper heat-shrink tubing and electrical tape.

Step 4: Sensor Replacement and Calibration If electrical tests confirm sensor failure, replace with a genuine Komatsu speed sensor (part number specific to PC110-8M0). After installation, torque the mounting bolt to 10-12 Nm and ensure proper air gap between sensor tip and reluctor ring (typically 0.5-1.5mm). Clear the fault code using Komatsu diagnostic software (KTCS) or by disconnecting the battery for 15 minutes.

Crucial for Used Excavators: Before replacing the sensor, thoroughly inspect the flywheel reluctor ring for missing or damaged teeth—a common issue on high-hour machines that causes false speed sensor codes. Also check for excessive engine vibration from worn motor mounts that can accelerate sensor and harness failure.

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Disclaimer: This guide provides general diagnostic information for Komatsu PC110-8M0 excavators. Always consult the manufacturer's service manual for exact specifications and procedures. For complex electrical issues or if you're uncomfortable performing these diagnostics, contact a certified Komatsu technician or qualified heavy equipment mechanic.