What is Sany Excavator Fault Code P268?

Fault Code P268 indicates an Engine Coolant Temperature (ECT) Sensor Circuit High Voltage condition in Sany excavators. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal from the coolant temperature sensor, typically exceeding 4.8-5.0 volts. The ECT sensor plays a critical role in engine management by monitoring coolant temperature and providing data that the ECM uses to adjust fuel injection timing, idle speed, and emission controls. When this circuit fails, the ECM cannot accurately determine engine operating temperature, potentially leading to inefficient combustion, increased emissions, and engine protection mode activation.

Common Symptoms

When Code P268 is active on your Sany excavator, you may experience:

• Check Engine Light (CEL) or malfunction indicator lamp illuminated on the dashboard
• Engine derate mode activated, limiting power output to prevent potential overheating damage
• Hard starting conditions, especially during cold weather, as the ECM defaults to a pre-programmed temperature value
• Rough idling or poor fuel economy due to incorrect fuel mixture calculations
• Cooling fan running continuously at high speed, regardless of actual engine temperature

Potential Causes

Several factors can trigger P268 in used Sany excavators:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing against frame components or engine mounts (common wear point near the thermostat housing)
• Failed coolant temperature sensor with internal resistance breakdown, particularly in machines with 5,000+ operating hours
• Corroded or loose connector pins at the sensor or ECM connection points due to moisture intrusion
• Damaged ECM wiring harness from rodent activity or improper previous repairs
• Faulty ECM (less common) with internal circuit board issues affecting the sensor input channel

How to Troubleshoot and Fix Code P268

Step 1: Visual Inspection Begin by inspecting the ECT sensor connector located near the thermostat housing. Check for corrosion, bent pins, or moisture. On used excavators, examine the entire wiring harness for obvious damage, particularly where it contacts metal surfaces or passes through grommets.

Step 2: Sensor Resistance Testing Disconnect the ECT sensor and measure resistance using a digital multimeter. At room temperature (68°F/20°C), resistance should typically read 2,000-3,000 ohms. Compare readings against Sany specifications. A reading of infinite resistance confirms sensor failure.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition on (engine off), 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 signal wire and ground wire back to the ECM for breaks or shorts.

Step 4: Harness Continuity Test Test continuity between the sensor connector and ECM pins using wiring diagrams. For used machines, pay special attention to connector terminals for corrosion—clean with electrical contact cleaner if necessary.

Step 5: Component Replacement Replace the ECT sensor if testing confirms failure. Use OEM or quality aftermarket parts to ensure proper resistance curves. Clear codes using Sany diagnostic software and perform a test cycle.

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Disclaimer: This guide provides general troubleshooting information. Always consult your Sany service manual and consider professional diagnostic services for complex electrical issues, especially on used equipment where multiple system degradation may be present.