Komatsu PC400-8 Fault Code E-17: Complete Diagnostic Guide

What is Komatsu PC400-8 Fault Code E-17?

Fault Code E-17 on the Komatsu PC400-8 indicates a malfunction in the hydraulic pump control system, specifically related to the pump discharge pressure sensor circuit or abnormal pressure readings. This code is triggered when the Electronic Control Module (ECM) detects voltage irregularities, sensor signal loss, or pressure values outside the manufacturer's specified parameters in the main hydraulic pump system.

This fault is critical for the PC400-8 because the hydraulic pump control system directly manages excavator performance, fuel efficiency, and component protection. When E-17 activates, the machine may enter a derated mode to prevent catastrophic pump or hydraulic system damage, significantly impacting productivity on job sites.

Common Symptoms

When Code E-17 is active, operators typically experience:

• Warning light illumination on the monitor panel with reduced hydraulic power
• Sluggish or unresponsive boom, arm, or bucket movements
• Automatic engine derate limiting RPM to protect the hydraulic system
• Intermittent loss of hydraulic functions during operation, especially under heavy loads
• Audible alarm accompanied by error message display on the multi-monitor

Potential Causes

The most common technical causes for E-17 on used PC400-8 excavators include:

• Pump discharge pressure sensor failure due to internal component wear or contamination
• Damaged or corroded wiring harness at known rub points near the pump mounting area
• Connector corrosion at the sensor plug, particularly on machines operating in wet or coastal environments
• Hydraulic oil contamination causing sensor membrane damage or false readings
• ECM calibration drift or software issues in older machines with high operating hours
• Voltage supply problems from damaged power circuits or poor ground connections

How to Troubleshoot and Fix Code E-17

Step 1: Initial Inspection Connect Komatsu diagnostic software (KOMTRAX Plus or equivalent) to retrieve active and stored codes. Record all freeze-frame data showing pressure readings at fault occurrence. Visually inspect the pump discharge pressure sensor and wiring harness for obvious damage, oil contamination, or connector corrosion.

Step 2: Electrical Testing Using a digital multimeter, check sensor supply voltage (should be 5V ±0.25V) and signal return voltage with the key on, engine off. Inspect harness continuity from sensor to ECM, paying special attention to wire routing near the hydraulic pump where vibration and heat cause insulation breakdown in used machines.

Step 3: Sensor and Hydraulic Verification Test sensor resistance according to Komatsu specifications (typically 200-400 ohms depending on temperature). If electrical values are correct, verify actual hydraulic pressure using a mechanical pressure gauge at the test port. Compare readings to sensor output voltage to identify sensor calibration drift—common in excavators exceeding 8,000 operating hours.

Step 4: Component Replacement and Verification Replace faulty sensors with genuine Komatsu parts to ensure proper ECM communication. Clean all connector pins with electrical contact cleaner and apply dielectric grease. After repairs, clear codes, perform a complete hydraulic system function test, and monitor for code recurrence over several operating cycles.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu PC400-8 service manual and consider professional diagnostic assistance for complex hydraulic system issues, especially on used equipment with unknown maintenance history.