Komatsu PC160LC-7 Fault Code E115: Technical Guide

What is Komatsu PC160LC-7 Fault Code E115?

Fault Code E115 on the Komatsu PC160LC-7 indicates a malfunction in the engine speed sensor circuit, specifically detecting an abnormal signal or loss of communication between the engine speed sensor and the Engine Control Module (ECM). This code typically appears when the ECM cannot properly read engine RPM data from the crankshaft position sensor.

The engine speed sensor (also called the crankshaft position sensor) is critical for proper fuel injection timing, engine speed control, and overall engine performance on the Komatsu SAA4D102E-2 engine. Without accurate RPM data, the ECM cannot optimize fuel delivery, causing performance degradation or complete shutdown. For used excavators, this sensor circuit is particularly vulnerable to environmental contamination, wiring degradation, and connector corrosion from years of operation in harsh conditions.

Common Symptoms

When Code E115 is active on your PC160LC-7, you may experience:

• Engine warning light illuminated on the instrument panel (amber or red depending on severity)
• Hard starting or failure to start, as the ECM cannot determine crankshaft position
• Rough idling or erratic engine speed with noticeable RPM fluctuations
• Engine stalling during operation, especially under load
• Power derate mode where the machine limits maximum engine speed to protect components

Potential Causes

The most common technical causes for Code E115 on used PC160LC-7 excavators include:

• Failed engine speed sensor due to internal component degradation or heat damage
• Damaged sensor wiring harness, particularly at flex points near the engine mount or along the frame rail where rubbing commonly occurs
• Corroded or loose electrical connectors at the sensor or ECM connection points
• Damaged reluctor ring on the crankshaft (rare but possible after major engine work)
• ECM internal fault affecting the sensor input circuit
• Contamination on the sensor face from oil leaks, metal debris, or carbon buildup reducing signal quality

How to Troubleshoot and Fix Code E115

Step 1: Visual Inspection Begin by locating the engine speed sensor on the bell housing area of the SAA4D102E-2 engine. Inspect the sensor mounting for security, checking for oil leaks or physical damage. Examine the entire wiring harness from sensor to ECM, looking specifically for abrasion points, heat damage, or wire breaks common at the engine-to-frame transition points on used machines.

Step 2: Connector and Continuity Testing Disconnect the sensor connector and inspect for corrosion, bent pins, or moisture intrusion—extremely common on older excavators. Using a digital multimeter, check for continuity in the wiring between the sensor connector and the ECM connector (typically requires the machine's wiring diagram). Resistance should be less than 1 ohm per wire.

Step 3: Sensor Resistance Check Measure the engine speed sensor resistance directly at the sensor connector. Specifications typically range between 190-250 ohms at 68°F (20°C), though consult your service manual for exact values. Values outside this range indicate sensor failure.

Step 4: Signal Testing If resistance checks pass, use Komatsu diagnostic software (KOMTRAX or compatible scan tool) to monitor live sensor output while cranking the engine. The ECM should receive a pulsing AC voltage signal (typically 0.5-3 volts). No signal indicates sensor failure or air gap issues.

Step 5: Air Gap Verification For used excavators, verify the sensor air gap to the reluctor ring is within specification (typically 0.5-1.5mm). Excessive wear or incorrect installation can prevent proper signal generation.

Step 6: Component Replacement Replace failed components systematically: start with the sensor if faulty, then address wiring issues. When installing a new sensor on used equipment, clean the mounting surface thoroughly and apply anti-seize to threads. Always clear codes and test operation before returning the machine to service.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and seek qualified technician assistance for complex electrical diagnostics or repairs.