Komatsu PC120-6 Fault Code E217: Complete Diagnostic Guide

What is Komatsu PC120-6 Fault Code E217?

Fault Code E217 indicates a malfunction in the hydraulic pump solenoid proportional control circuit, specifically detecting an abnormal voltage or current signal from the pump control solenoid valve. This code is triggered when the Electronic Control Module (ECM) detects that the electrical signal to the hydraulic pump's proportional solenoid is outside acceptable parameters (typically 0.5-4.5V range).

This fault is critical for the PC120-6 because the proportional solenoid regulates hydraulic pump output based on operator demand. When this circuit fails, the machine cannot properly modulate hydraulic flow, directly impacting excavator performance, fuel efficiency, and operational safety. The PC120-6's load-sensing system relies on precise solenoid control to match engine output with hydraulic demand.

Common Symptoms

• Intermittent or continuous hydraulic power loss during operation, particularly noticeable during combined functions
• ECM warning light illuminated on the instrument panel (amber or red depending on severity)
• Rough or erratic pump response when operating control levers, with delayed reaction times
• Machine enters derate mode, limiting engine RPM to approximately 1500-1800 RPM to protect components
• Abnormal whining or cavitation noises from the main hydraulic pump area

Potential Causes

The most common causes for E217 in used PC120-6 excavators include:

• Harness chafing at the pump mounting bracket where wires contact metal edges (known wear point on this model)
• Corroded or moisture-contaminated connectors at the solenoid connection point near the pump
• Failed proportional solenoid coil due to internal short circuit or open winding (resistance should be 18-22 ohms)
• ECM internal driver circuit failure, particularly in machines with 8,000+ operating hours
• Damaged wiring in the engine compartment from heat exposure or rodent damage
• Poor ground connection at the pump mounting bolt (G203 ground point)

How to Troubleshoot and Fix Code E217

Step 1: Visual Inspection Begin by inspecting the solenoid wiring harness from the ECM to the pump. On used PC120-6 machines, check the harness routing near the right-side engine mount where rubbing commonly occurs. Examine all connectors for corrosion, bent pins, or moisture intrusion. Clean connectors with electrical contact cleaner.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure coil resistance. It should read 18-22 ohms at room temperature. Check for voltage supply at the harness side with ignition on—you should see approximately 12V on the power wire. Verify ground continuity between solenoid ground and battery negative (less than 1 ohm resistance).

Step 3: Signal Verification Connect Komatsu diagnostic software (KOMTRAX or compatible scanner) to monitor live solenoid command signals. Operate controls while observing commanded vs. actual current values. Deviations exceeding 15% indicate ECM driver issues or solenoid mechanical binding.

Step 4: Component Replacement If resistance or voltage tests fail, replace the proportional solenoid valve (part approximately $280-450 for genuine Komatsu). For used excavators, always replace the mating connector and apply dielectric grease to prevent future corrosion. Clear codes and perform calibration using diagnostic software.

Disclaimer: This guide provides general troubleshooting information. Hydraulic system repairs involve high-pressure components and electrical diagnostics requiring specialized tools. Consult qualified Komatsu technicians or certified heavy equipment mechanics for complex repairs, especially on machines still under warranty or service agreements.