What is Sany General Fault Code P152?

Fault Code P152 on Sany excavators indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor Circuit – specifically a high voltage condition or open circuit detected by the Engine Control Module (ECM). This diagnostic trouble code (DTC) means the ECM is receiving a voltage signal from the coolant temperature sensor that exceeds normal operating parameters, typically above 4.8-5.0 volts, or no signal at all due to circuit discontinuity.

The ECT sensor plays a critical role in engine management for Sany excavators. It monitors coolant temperature and sends real-time data to the ECM, which adjusts fuel injection timing, idle speed, and cooling fan operation accordingly. When P152 triggers, the ECM cannot accurately determine engine temperature, forcing the system into a failsafe mode that can significantly impact machine performance and potentially cause engine damage if ignored.

Common Symptoms

• Check Engine Light or malfunction indicator lamp illuminated on the instrument cluster
• Engine running in cold-start mode continuously, resulting in rough idle and excessive fuel consumption
• Cooling fan running constantly at high speed regardless of actual engine temperature
• Reduced engine power or derate mode activation to prevent potential overheating damage
• Difficulty starting when the engine is warm, or extended cranking times

Potential Causes

The most common technical causes for P152 on used Sany excavators include:

• Failed ECT sensor due to internal resistance breakdown (common after 5,000+ operating hours)
• Open circuit in the sensor wiring harness, particularly at known rub points near the engine block or valve cover
• Corroded or loose connector pins at the ECT sensor plug – moisture intrusion is common in aged machines
• Damaged wiring insulation from heat exposure, rodent damage, or abrasion against engine components
• ECM internal fault (less common) where the temperature sensor input circuit has failed
• Improper sensor installation or aftermarket sensor with incorrect resistance specifications

How to Troubleshoot and Fix Code P152

Step 1: Visual Inspection Begin with a thorough inspection of the ECT sensor and its wiring harness. The sensor is typically located on the engine block near the thermostat housing. Check for physical damage, coolant leaks around the sensor, corroded connector pins, or damaged wire insulation. On used excavators, pay special attention to harness routing where wires may rub against engine mounts or sharp edges.

Step 2: Electrical Testing Using a digital multimeter, disconnect the ECT sensor connector and measure resistance across the sensor terminals. At approximately 68°F (20°C), resistance should read between 2,000-3,000 ohms (consult Sany service manual for exact specifications). If the reading shows infinite resistance (open circuit) or zero ohms (short circuit), replace the sensor. Also check for voltage supply at the harness connector with ignition on – you should see approximately 5 volts reference voltage from the ECM.

Step 3: Wiring Harness Continuity Test continuity between the ECT sensor connector and the ECM connector using a wiring diagram specific to your Sany model. Check for shorts to ground or power. On older machines, inspect harness sections that pass near hot exhaust components or moving parts where insulation deterioration is common.

Step 4: Component Replacement and Verification Replace faulty components using OEM Sany parts when possible, as aftermarket sensors may have incorrect calibration curves. After replacement, clear the fault code using Sany diagnostic software or a compatible scan tool, and monitor coolant temperature readings during a full warm-up cycle to ensure proper operation.

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Disclaimer: This guide provides general troubleshooting information for Sany excavator fault code P152. Always consult the manufacturer's service manual for your specific model and serial number. If you're uncomfortable performing electrical diagnostics, seek assistance from a certified Sany technician or qualified heavy equipment mechanic.