Komatsu PC200-7 Fault Code E-31: Technical Guide

What is Komatsu PC200-7 Fault Code E-31?

Fault Code E-31 on the Komatsu PC200-7 indicates a malfunction in the pump flow control solenoid valve circuit. This code specifically signals that the electronic control module (ECM) has detected an abnormal electrical condition in the hydraulic pump's proportional solenoid valve system, which regulates pump displacement and hydraulic flow.

The PC200-7's load sensing system relies on this solenoid to optimize fuel efficiency while maintaining hydraulic power. When this circuit fails, the excavator cannot properly match pump output to operational demands, directly affecting performance and potentially causing excessive fuel consumption. This is particularly critical in the PC200-7's variable displacement piston pump system, where precise electronic control ensures the machine operates within designed parameters.

Common Symptoms

When Code E-31 is active, operators typically experience:

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Monitor display warning showing the fault code with possible amber or red warning light
• Loss of fine control during precision work, as the pump defaults to a fixed displacement mode
• Increased engine RPM without corresponding hydraulic response, indicating pump flow mismatch
• Intermittent hydraulic surging or erratic control lever response during combined operations

Potential Causes

The most common technical causes for E-31 in used PC200-7 excavators include:

• Solenoid valve coil failure due to heat cycling and age-related insulation breakdown (resistance typically measures outside 10-50 ohms specification)
• Wiring harness damage at known rub points near the pump mounting area where protective loom deteriorates from vibration
• Connector corrosion on the 3-pin solenoid connector, especially in machines operated in wet or coastal environments
• ECM pin corrosion or loose connections at the controller harness (check pins 32-34 on main connector)
• Voltage supply issues from degraded main power harness or poor grounding at frame mounting points
• Internal solenoid valve contamination from degraded hydraulic oil allowing spool sticking

How to Troubleshoot and Fix Code E-31

Step 1: Visual Inspection Begin with the pump-mounted proportional solenoid valve (located on the left side of the main hydraulic pump). Disconnect the electrical connector and inspect for oil contamination, bent pins, or green corrosion. On used excavators, check the wire harness routing—the PC200-7 has a known wear point where the harness contacts the pump cooling fan shroud.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid coil resistance. With the connector disconnected and ignition off, check resistance between the two solenoid terminals—specification is 20-30 ohms at 20°C. Next, perform a voltage supply test: reconnect the solenoid, turn the key to ON (engine off), and backprobe the connector. You should see approximately 12 volts on the power supply wire.

Step 3: Circuit Integrity Check Test for short circuits by measuring resistance between each solenoid wire and chassis ground (should read infinite/open circuit). Check ECM connector C2 for corrosion and verify ground circuit continuity (less than 1 ohm to frame). For machines with over 8,000 hours, inspect the main engine harness where it passes through the bulkhead—chafing here creates intermittent faults.

Step 4: Component Replacement or Cleaning If resistance readings are out of specification, replace the solenoid valve assembly (Komatsu part 723-46-13200 or equivalent). Before replacing, ensure hydraulic oil quality meets specifications—contaminated oil accelerates valve failures. If electrical tests pass but symptoms persist, the issue may be mechanical valve sticking; attempt cleaning the valve body or replacing the complete pump control valve.

Professional Consultation: While these diagnostic procedures are proven for the PC200-7 platform, excavator hydraulic and electrical systems are complex. If fault persists after basic troubleshooting, consult a certified Komatsu technician or use Komatsu diagnostic software (KOMTRAX or service laptop) to perform active output tests and confirm ECM functionality.