What is Komatsu PC210-10 Fault Code E-38?

Fault Code E-38 on the Komatsu PC210-10 excavator indicates a Hydraulic Pump Control Solenoid Valve (PC-EPC valve) circuit malfunction. This code is triggered when the Engine Control Module (ECM) detects abnormal voltage or current in the proportional control solenoid that regulates main hydraulic pump displacement.

The PC-EPC valve (Pump Control - Electronic Proportional Control) is critical to the PC210-10's CLSS (Closed-Center Load Sensing System) hydraulic architecture. This solenoid receives PWM signals from the ECM to modulate pump swash plate angle based on operator demand and engine load conditions. When this circuit fails, the excavator cannot properly match hydraulic flow to work requirements, severely impacting productivity and fuel efficiency. On used machines, this fault often stems from electrical degradation rather than mechanical pump failure, making proper diagnosis essential before expensive component replacement.

Common Symptoms

• Reduced hydraulic power across all functions, with sluggish boom, arm, and swing response regardless of engine RPM
• Intermittent or constant engine derate, limiting maximum RPM to protect the drivetrain from uncontrolled pump loads
• Warning lamp illumination on the monitor panel, often accompanied by a specific fault message displaying "E-38" or "Hydraulic System Error"
• Erratic pump noise or unusual whining during operation as the pump defaults to mechanical backup control
• Increased fuel consumption due to inefficient pump regulation and engine working harder to compensate for flow mismatches

Potential Causes

The most common technical failures triggering E-38 on used PC210-10 excavators include:

• Broken or corroded wiring in the harness between the ECM and PC-EPC valve, particularly at flex points near the pump mounting bracket where vibration causes conductor fatigue
• Failed PC-EPC solenoid coil, exhibiting out-of-spec resistance (normal range: 3-5 ohms) due to heat exposure or internal short circuits
• Connector pin corrosion at the 3-pin Deutsch connector on the solenoid valve, especially on machines operated in wet or coastal environments
• ECM internal driver circuit failure, though less common, can prevent proper PWM signal generation
• Intermittent open circuits caused by worn harness insulation rubbing against the pump case or hydraulic lines

How to Troubleshoot and Fix Code E-38

Step 1: Initial Electrical Verification Connect a multimeter to the PC-EPC solenoid connector (engine off, key on). Measure resistance across the solenoid terminals—specification is 3-5 ohms. If reading shows infinity (open circuit) or below 2 ohms (short), the solenoid has failed internally and requires replacement.

Step 2: Harness and Connector Inspection Physically trace the wire harness from the ECM (located behind the operator cab) to the pump-mounted solenoid. On used excavators, inspect thoroughly for chafing, cuts, or green corrosion at connector pins. Use electrical contact cleaner and dielectric grease on all connections. Check for voltage supply: with key on, you should read battery voltage (12-14V) on the power supply pin.

Step 3: Dynamic Circuit Testing Using Komatsu KOMTRAX diagnostic software or compatible scan tool, command the PC-EPC valve while monitoring live data. Observe if the ECM can vary the PWM duty cycle (typically 10-90%) and whether actual current matches commanded values. If commands don't produce corresponding current changes, suspect ECM driver failure. Clear codes after repairs and perform a hydraulic load test to verify proper pump response across all operating ranges.

For used excavators, always perform a complete harness continuity test and inspect for previous repair attempts or aftermarket splices that may cause intermittent faults.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnosis for complex electrical or hydraulic system failures.