What is Kato General Fault Code P1568?

Fault Code P1568 indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor Circuit - High Input condition. This diagnostic trouble code triggers when the Engine Control Module (ECM) detects an abnormally high voltage signal from the coolant temperature sensor, typically above 4.8 volts, suggesting either an open circuit or sensor failure.

In Kato excavators, the ECT sensor plays a critical role in engine management by monitoring coolant temperature and relaying this data to the ECM. The ECM uses this information to adjust fuel injection timing, idle speed, and engine protection protocols. When P1568 activates, the ECM cannot accurately determine engine temperature, potentially leading to improper fuel mixture, increased emissions, and inadequate engine protection from overheating conditions.

Common Symptoms

• Check Engine Light or malfunction indicator lamp illuminated on the dashboard
• Engine fails to reach proper operating temperature or runs in a default "cold start" mode continuously
• Rough idle or poor engine performance, particularly during warm-up phases
• Increased fuel consumption due to ECM defaulting to rich fuel mixture settings
• In severe cases, engine derate mode may activate to prevent potential overheating damage

Potential Causes

The most common causes of P1568 in used Kato excavators include:

• ECT sensor internal failure causing open circuit conditions (common in machines with 5,000+ operating hours)
• Damaged or corroded wiring harness connections at the sensor plug, particularly where the harness routes near hot exhaust components
• Broken or frayed wires in the sensor circuit due to vibration wear at known rub points near the engine block
• Faulty ECM connections or corroded pins in the ECM connector
• Coolant contamination causing sensor element degradation in older machines
• Previous repair attempts using incorrect sensor specifications or aftermarket sensors with incompatible resistance values

How to Troubleshoot and Fix Code P1568

Step 1: Visual Inspection Begin by inspecting the ECT sensor and its wiring harness for obvious damage. Check for corroded connectors, oil contamination, or physical damage to wires. On used excavators, pay special attention to harness routing near moving components or heat sources where insulation may have deteriorated over time.

Step 2: Electrical Testing Disconnect the ECT sensor connector and use a digital multimeter to measure resistance across the sensor terminals. Compare readings against Kato's specification chart (typically 2,000-3,000 ohms at 20°C). If readings show infinite resistance (open circuit) or are significantly outside specifications, replace the sensor. Next, check for continuity in the wiring harness from sensor to ECM.

Step 3: Circuit Voltage Check With the ignition on and sensor disconnected, measure voltage at the harness connector. You should see approximately 5 volts reference voltage from the ECM. If voltage is absent or incorrect, trace the circuit for breaks or check ECM power supply and ground connections.

Step 4: Advanced Diagnostics Use Kato-compatible diagnostic software to monitor live sensor data and verify the ECM is receiving proper signals. Clear codes after repairs and perform a test run, monitoring coolant temperature response. For used machines, consider replacing the entire sensor harness if multiple corrosion points are found, as intermittent connection issues will persist.

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Disclaimer: This guide provides general troubleshooting information for P1568 fault codes. Always consult the official Kato service manual for your specific model and serial number. If you're unfamiliar with electrical diagnostics or working on heavy equipment, seek assistance from a qualified diesel technician or authorized Kato service center.