Komatsu PC400LC-6 Fault Code E207: Complete Diagnostic Guide

What is Komatsu PC400LC-6 Fault Code E207?

Fault Code E207 indicates a malfunction in the hydraulic pump control system, specifically related to the pump flow control solenoid valve circuit or its associated wiring harness. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage or resistance reading from the pump control solenoid, which regulates hydraulic flow based on operational demands.

In the PC400LC-6 model, this system is critical for maintaining optimal hydraulic performance and fuel efficiency. The pump flow control solenoid adjusts the swash plate angle of the main hydraulic pumps, directly affecting machine responsiveness and power delivery. When this circuit fails, the excavator may default to a fixed displacement mode, significantly impacting productivity.

Common Symptoms

When Code E207 is active, operators typically experience:

• Reduced hydraulic power across all functions (boom, arm, bucket, and swing operations feel sluggish)
• Warning light illumination on the monitor panel, often accompanied by an audible alarm
• Increased fuel consumption due to the pump operating at maximum displacement regardless of load requirements
• Erratic hydraulic response or inconsistent cycle times during operation
• Machine entering derate mode in severe cases, limiting engine RPM to protect the hydraulic system

Potential Causes

The most common technical reasons for E207 on used PC400LC-6 excavators include:

• Solenoid valve coil failure due to age, heat exposure, or internal short circuits (resistance typically should read 20-30 ohms)
• Wiring harness damage at known rub points near the hydraulic pump mounting area where cables contact the frame
• Corroded or loose connector pins at the solenoid valve plug, especially on machines operating in wet or corrosive environments
• ECM internal circuit degradation affecting the solenoid driver output (less common but possible in high-hour machines)
• Voltage supply issues from the main power harness, including poor grounds or damaged relay contacts

How to Troubleshoot and Fix Code E207

Step 1: Visual Inspection Begin by inspecting the pump control solenoid valve located on the main hydraulic pump assembly. Check for physical damage, oil contamination on connectors, and verify the wiring harness routing. On used excavators, pay special attention to harness wear points where cables pass through metal brackets or contact the pump housing.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure coil resistance. Specifications typically range from 20-30 ohms at room temperature. Next, check for supply voltage (usually 12-24V depending on circuit design) at the harness side with the ignition on. Verify ground continuity by measuring resistance between the solenoid ground pin and chassis ground (should be less than 1 ohm).

Step 3: Advanced Diagnostics Connect Komatsu diagnostic software (KOMTRAX or compatible scan tool) to monitor real-time solenoid command signals from the ECM. Compare commanded versus actual current flow. If the ECM commands proper voltage but the solenoid doesn't respond, replace the solenoid valve. If no command signal exists, suspect ECM issues or main harness faults between the controller and pump.

Step 4: Repair and Verification For used machinery, clean all connector pins with electrical contact cleaner and apply dielectric grease before reassembly. Replace damaged harness sections with OEM-spec wire and ensure proper routing with new protective loom. After repairs, clear the fault code and perform a full hydraulic function test under load.

---

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