What is Kato HD820V Fault Code P1573?

Fault Code P1573 on the Kato HD820V excavator indicates a Fuel Injector Circuit Malfunction - Cylinder #3. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal electrical signal or response from the fuel injector circuit for the third cylinder. The ECM continuously monitors injector driver circuits for proper voltage, resistance, and response time during engine operation.

This code is critical for the HD820V's performance because improper injector operation directly affects fuel delivery, combustion efficiency, and engine power output. In Kato's diesel engines, precise fuel injection timing and volume are essential for meeting emission standards, preventing engine damage, and maintaining hydraulic system performance. When P1573 is active, the ECM may implement power derate strategies to protect the engine from uncontrolled combustion or mechanical damage.

Common Symptoms

• Engine misfiring or rough idle, particularly noticeable during warm-up or under load
• Reduced hydraulic power and slower cycle times during digging or lifting operations
• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Black or white exhaust smoke indicating incomplete combustion from cylinder #3
• Power derate mode activated by the ECM, limiting engine RPM to 1500-1800 range

Potential Causes

The most common causes of P1573 on used HD820V excavators include:

• Faulty fuel injector on cylinder #3 due to worn solenoid windings, stuck pintle valves, or internal coil failure
• Damaged injector harness or connector corrosion, especially at the cylinder #3 injector plug (known wear point on HD820 models)
• Broken or frayed wiring between the ECM and injector, often caused by harness rubbing against engine components near the valve cover
• Failed ECM injector driver circuit for cylinder #3, though less common than external wiring issues
• Poor electrical ground connections at the engine block or ECM mounting points affecting injector circuit integrity
• Contaminated fuel causing injector clogging or carbon buildup restricting fuel flow

How to Troubleshoot and Fix Code P1573

Step 1: Visual Inspection Begin by inspecting the injector wiring harness from the ECM to cylinder #3. On used HD820V machines, check for harness wear where it passes near the exhaust manifold and valve cover edges. Examine the injector connector for corrosion, bent pins, or oil contamination. Clean connectors with electrical contact cleaner and ensure proper seating.

Step 2: Electrical Testing Using a digital multimeter, disconnect the injector connector at cylinder #3 and measure resistance across the injector terminals. Typical resistance should be 0.3-0.8 ohms for Kato injectors. Check for continuity between the ECM connector and injector harness terminals. Inspect for short circuits to ground by measuring resistance between each injector wire and engine ground (should read open circuit/infinite resistance).

Step 3: Injector Function Test Connect Kato diagnostic software (or compatible J1939 diagnostic tool) to verify injector command signals from the ECM. Perform an injector cutout test to confirm cylinder #3 contribution to engine operation. If electrical tests pass but the code persists, the injector solenoid itself may have failed internally and requires replacement.

Step 4: Swap Testing (Used Equipment Verification) For used excavators, consider swapping the cylinder #3 injector with another cylinder (such as #4) to determine if the fault follows the injector or remains at cylinder #3. If the code changes to P1574 (cylinder #4), the injector is faulty. If P1573 remains, focus on harness repair or ECM driver circuit issues.

Critical for Used Machines: Before replacing expensive components, thoroughly inspect all connector terminals for "green corrosion" and check harness routing for modifications from previous repairs. Verify battery voltage (should be 24-28V on HD820V) and charging system output, as low voltage can trigger false injector codes.

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Disclaimer: This guide provides general troubleshooting information for Kato HD820V fault code P1573. Always consult the manufacturer's service manual for model-specific procedures. If unfamiliar with high-pressure fuel systems or electrical diagnostics, contact a certified Kato technician to prevent injury or equipment damage.