What is Kato HD820-1 Fault Code E70?

Fault Code E70 on the Kato HD820-1 excavator indicates a hydraulic pump pressure sensor abnormality or main pump control system malfunction. This diagnostic trouble code (DTC) is triggered when the engine control module (ECM) detects voltage readings from the hydraulic pressure sensor that fall outside the manufacturer's specified range, typically indicating sensor failure, wiring issues, or actual hydraulic system pressure problems.

This code is critical for the HD820-1 because the hydraulic pump system is the heart of excavator operation. The ECM relies on accurate pressure feedback to optimize pump output, control swing speed, and prevent hydraulic system damage. When E70 appears, the machine may enter a derate mode to protect components, significantly impacting job site productivity.

Common Symptoms

• Reduced hydraulic power across all functions (boom, arm, bucket, and swing movements become sluggish)
• Warning light illumination on the instrument cluster, often accompanied by an audible alarm
• Erratic hydraulic response where functions work intermittently or inconsistently
• Engine derating or automatic RPM reduction to protect the hydraulic system
• Display panel error message showing E70 code on the multi-function monitor

Potential Causes

The most common causes of Code E70 on used Kato HD820-1 excavators include:

• Hydraulic pressure sensor failure due to age, contamination, or internal component wear (extremely common on machines with 5,000+ hours)
• Damaged or corroded wiring harness near the main pump area where cables experience vibration and hydraulic fluid exposure
• Connector corrosion at the sensor plug, particularly on machines operated in wet or marine environments
• ECM communication errors caused by poor ground connections or voltage irregularities
• Actual hydraulic system issues such as worn pump components, contaminated hydraulic oil, or relief valve malfunction
• Previous repair interference where harness routing was altered during pump or engine service on used equipment

How to Troubleshoot and Fix Code E70

Step 1: Visual Inspection Begin by inspecting the hydraulic pump pressure sensor located on the main hydraulic pump assembly. Check for physical damage, oil contamination on the connector, or obvious harness wear. On used excavators, examine known rub points where the harness contacts frame members near the pump.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. Compare readings against Kato specifications (typically 200-400 ohms at 20°C). Check supply voltage at the harness connector with ignition on—should read approximately 5 volts. Test harness continuity between the sensor connector and ECM pins to identify open circuits.

Step 3: Connector and Ground Verification Clean all connector terminals with electrical contact cleaner and apply dielectric grease. Verify the ECM ground circuit has less than 0.5 ohms resistance to chassis ground. Corroded grounds are a frequent issue on older machines.

Step 4: Sensor Replacement and System Testing If testing confirms sensor failure, replace with a genuine Kato pressure sensor or OEM-equivalent part. After replacement, clear codes using Kato diagnostic software or the manual reset procedure. Perform a hydraulic pressure test to confirm actual system pressure meets specifications (typically 320-350 bar).

Step 5: Advanced Diagnostics If the code persists after sensor replacement, test actual hydraulic pump output pressure with a hydraulic pressure gauge installed at the test port. Low pressure indicates pump wear—common on high-hour used excavators—requiring pump rebuild or replacement.

Disclaimer: This guide provides general troubleshooting information for the Kato HD820-1. Hydraulic systems operate under extreme pressure and require specialized knowledge. Always consult the official Kato service manual and consider professional diagnostic assistance for complex issues or when working with used equipment with unknown maintenance history.