What is Komatsu PC450-7 Fault Code E117?

Fault Code E117 on the Komatsu PC450-7 indicates a malfunction in the engine controller's (ECM) communication circuit with the hydraulic pump flow control solenoid valve. This diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) has detected an abnormal voltage or current flow in the electrical circuit controlling the pump's flow compensation system, which is critical for managing hydraulic power distribution.

On the PC450-7, this circuit regulates how much hydraulic flow reaches implements versus travel motors. When E117 triggers, the ECM loses proper command over the variable displacement piston pump, potentially causing the machine to enter a derated performance mode to prevent component damage. This fault is particularly significant because the PC450-7's fuel efficiency and cycle times depend heavily on precise pump flow modulation matched to engine load.

Common Symptoms

When Code E117 is active, operators typically experience:

• Check engine warning light illuminated on the instrument panel, often accompanied by a specific hydraulic system indicator
• Sluggish hydraulic response or inconsistent boom/arm speed during combined functions
• Reduced digging force as the system may default to a conservative flow setting
• Increased fuel consumption due to improper matching between engine RPM and hydraulic demand
• Intermittent loss of fine control during precision work, especially noticeable when grading or performing detailed excavation

Potential Causes

The most common technical failures causing E117 on used PC450-7 excavators include:

• Failed flow control solenoid valve – internal coil breakage or mechanical sticking (common after 8,000+ hours)
• Damaged wiring harness between ECM and solenoid, particularly where the harness passes near the swing motor or along the boom base (known rub point on this model)
• Corroded or loose connector pins at the C3 connector behind the operator's cab
• ECM internal driver circuit failure – less common but possible in machines with electrical system overvoltage history
• Contaminated hydraulic oil causing solenoid valve spool seizure
• Ground circuit interruption at frame grounding points (corrosion issue in coastal/salt-exposed machines)

How to Troubleshoot and Fix Code E117

Step 1: Visual Inspection Begin by inspecting the solenoid valve connector located on the main hydraulic pump. Check for oil contamination, pushed-back pins, or corrosion. On used excavators, this connector often accumulates hydraulic mist and dirt. Clean with electrical contact cleaner and verify pin seating.

Step 2: Electrical Testing Using a digital multimeter, backprobe the solenoid connector with the key on, engine off. Verify supply voltage (should read 24V DC). Then check solenoid resistance – the coil should measure 3-7 ohms. Values outside this range indicate solenoid replacement is needed.

Step 3: Harness Continuity Check Trace the wiring from the ECM connector C3 (pin 18) to the solenoid valve. Check for continuity and ensure resistance is below 0.5 ohms. Pay special attention to the harness section near the boom swing bearing – this is a common wear point where insulation breaks down on older PC450-7 machines.

Step 4: Monitor Live Data Connect Komatsu KOMTRAX diagnostic software or compatible scan tool. Monitor the ECM's commanded versus actual solenoid duty cycle. A discrepancy indicates either a failed solenoid or ECM driver issue.

Step 5: Ground Verification Check frame ground connections, especially G101 near the battery box. Clean contact surfaces and verify less than 0.1-ohm resistance to chassis ground.

For used machines, always inspect connector O-rings and apply dielectric grease during reassembly to prevent future corrosion-related faults.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues or if unfamiliar with high-voltage systems.