What is Komatsu PC220-8 Fault Code E-6?

Fault Code E-6 on the Komatsu PC220-8 excavator indicates a hydraulic pump flow control system malfunction, specifically related to the main pump control solenoid valve or its associated circuit. This code triggers when the Engine Control Module (ECM) detects abnormal electrical signals or mechanical performance from the proportional solenoid that regulates hydraulic pump displacement.

The PC220-8 uses sophisticated closed-center hydraulic load-sensing technology where the ECM continuously adjusts pump output based on operator demand. When E-6 appears, this critical feedback loop is compromised, directly impacting fuel efficiency, hydraulic response time, and overall machine productivity. For used excavators, this fault often stems from accumulated electrical degradation or mechanical wear in high-vibration mounting areas.

Common Symptoms

When Code E-6 is active, operators typically experience:

• Sluggish hydraulic response across all functions (boom, arm, bucket, swing)
• Erratic pump noise or unusual whining sounds during operation
• Warning lamp illumination on the monitor panel with simultaneous power derate
• Inconsistent digging force or inability to maintain constant working speed
• Excessive fuel consumption due to inefficient pump regulation

Potential Causes

The most common technical failures triggering E-6 in used PC220-8 machines include:

• Proportional solenoid valve coil failure (internal short or open circuit)
• Wiring harness damage at flex points near the pump mounting bracket—a known wear location on 5,000+ hour machines
• Corroded or loose connector pins at the main pump electrical harness (3-pin Deutsch connector)
• ECM internal driver circuit malfunction (less common but possible in high-hour units)
• Contaminated hydraulic oil causing mechanical sticking of the spool valve inside the solenoid assembly

How to Troubleshoot and Fix Code E-6

Step 1: Initial Electrical Verification
Using a digital multimeter, measure resistance across the solenoid coil terminals (disconnect harness first). Specification should read 8-12 ohms at room temperature. Readings below 5 ohms indicate a short; infinite resistance confirms an open circuit requiring solenoid replacement.

Step 2: Harness and Connector Inspection
Physically trace the pump control harness from the ECM to the solenoid valve. On used excavators, closely examine the section passing near the hydraulic pump mounting bolts—rubbing against metal edges commonly causes insulation wear. Check connector pins for green corrosion or bent terminals. Clean with electrical contact cleaner and apply dielectric grease.

Step 3: Voltage Supply Test
With ignition on (engine off), backprobe the harness connector to verify 12V supply voltage from the ECM. If voltage is absent, suspect ECM driver failure or upstream wiring issues. If voltage is present but the solenoid doesn't click when energized, replace the solenoid valve assembly.

Step 4: Hydraulic System Check
If electrical tests pass, remove the solenoid and inspect for metal contamination or varnish buildup on the spool. Flush with clean hydraulic fluid. Verify main hydraulic filter condition and oil cleanliness (ISO 18/16/13 or better required).

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