What is Kobelco SK330-8 Fault Code A035?

Fault Code A035 on the Kobelco SK330-8 excavator indicates a malfunction in the hydraulic pump delivery system, specifically related to the main pump's pressure sensor circuit or abnormal delivery pressure detection. This code triggers when the Electronic Control Module (ECM) detects inconsistent or out-of-range signals from the pump delivery pressure sensor, which monitors the hydraulic system's primary working pressure.

This diagnostic trouble code is critical because the SK330-8's hydraulic pump delivery system directly affects all machine functions—boom, arm, bucket, swing, and travel operations. The pressure sensor provides real-time feedback to the ECM, allowing the controller to optimize pump output, fuel efficiency, and prevent catastrophic hydraulic system damage. When A035 appears, the machine may enter a protective derate mode to prevent further damage to expensive hydraulic components, including the variable displacement piston pumps that can cost upwards of $15,000 to replace.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower cycle times for boom and arm movements
• Erratic operation where hydraulic functions momentarily lose power or respond inconsistently to joystick inputs
• Warning lamp illumination on the instrument cluster, often accompanied by an audible alarm
• Machine entering limp mode, limiting engine RPM to approximately 1,200-1,500 RPM regardless of throttle position
• Diagnostic display showing fault code A035 on the multi-function monitor panel

Potential Causes

The most common technical causes for A035 on used SK330-8 excavators include:

• Pressure sensor failure due to internal diaphragm deterioration or sensor element contamination from hydraulic fluid breakdown
• Wiring harness damage at known rub points near the pump mounting area where constant vibration causes wire insulation wear
• Connector corrosion at the sensor plug, particularly on machines operated in coastal or high-humidity environments
• Contaminated hydraulic fluid causing sensor port blockage or erratic pressure readings
• ECM calibration drift in older machines with 8,000+ operating hours
• Actual pump delivery issues including worn swash plate assemblies or servo piston problems creating abnormal pressure patterns

How to Troubleshoot and Fix Code A035

Step 1: Visual Inspection Begin by examining the pump delivery pressure sensor located on the main hydraulic pump housing. Check the electrical connector for corrosion, bent pins, or moisture intrusion. Inspect the wiring harness for approximately 18 inches back from the sensor, focusing on areas where the harness contacts metal edges or moving components—a common failure point on used excavators.

Step 2: Electrical Testing Using a digital multimeter, perform a resistance check across the sensor terminals with the connector disconnected and ignition off. The SK330-8 pressure sensor should typically read 250-350 ohms at room temperature. Check for supply voltage at the harness side (should be approximately 5.0V reference voltage from the ECM). Measure ground continuity to ensure less than 1 ohm resistance to chassis ground.

Step 3: Dynamic Pressure Testing Connect Kobelco diagnostic software (or compatible J1939 scan tool) to monitor live sensor data. Compare the displayed pressure values against a mechanical hydraulic pressure gauge installed at a test port. Discrepancies greater than 200 PSI indicate sensor replacement is needed. For used excavators, flush the sensor mounting port with clean hydraulic fluid to remove debris before installing a new sensor.

Step 4: Advanced Diagnostics If electrical testing passes but the code persists, perform a hydraulic pump flow test to rule out actual delivery problems. Worn pumps on high-hour machines may produce pressure fluctuations that trigger A035 even with functioning sensors. Check hydraulic filter condition and analyze a fluid sample for contamination indicating internal pump wear.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Kobelco service manual for your specific machine serial number and consider professional assistance for complex hydraulic system repairs. Improper diagnostics may lead to equipment damage or safety hazards.