What is Sany Excavator Fault Code P915?

Fault Code P915 indicates a malfunction in the engine coolant temperature sensor circuit or an out-of-range coolant temperature reading. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an abnormal voltage signal from the coolant temperature sensor (CTS), suggesting either a sensor failure, wiring issue, or actual overheating condition within the engine cooling system.

For Sany excavators, this code is critical because the ECM relies on accurate coolant temperature data to manage fuel injection timing, engine protection protocols, and emissions control. When P915 activates, the ECM may enter a derate mode to prevent catastrophic engine damage from overheating or operate on default temperature values, reducing machine efficiency and performance.

Common Symptoms

• Warning light illuminated on the instrument cluster, often accompanied by a coolant temperature gauge reading abnormally high or low
• Engine power reduction or derate mode activation, limiting hydraulic performance and digging force
• Rough idling or difficulty starting, especially in cold weather conditions
• Cooling fan running continuously at maximum speed regardless of actual engine temperature
• Error messages displayed on the digital monitor indicating temperature sensor faults

Potential Causes

The most common technical reasons for Code P915 on used Sany excavators include:

• Coolant temperature sensor failure due to age-related degradation or internal element breakdown
• Wiring harness damage at known rub points near the engine block or frame rails, particularly where harnesses contact metal surfaces
• Corroded or loose electrical connectors at the sensor plug, common in machines exposed to moisture or muddy job sites
• ECM software glitches or calibration drift in older control modules
• Actual engine overheating caused by low coolant levels, failed thermostat, or clogged radiator
• Short circuits or open circuits in the sensor signal wire between the CTS and ECM

How to Troubleshoot and Fix Code P915

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor location (typically on the engine block near the thermostat housing). Check for physical damage, coolant leaks, or corrosion on the sensor connector. On used excavators, pay special attention to harness wear points where cables may have rubbed against metal components over thousands of operating hours.

Step 2: Electrical Testing Using a digital multimeter, disconnect the CTS connector and measure the sensor's resistance at ambient temperature (typically 2,000-3,000 ohms at 20°C for most sensors). Compare readings against Sany specifications. Next, check for voltage supply at the harness connector—you should see approximately 5 volts reference voltage from the ECM with the key on, engine off.

Step 3: Circuit Continuity and Ground Testing Test for continuity between the sensor connector and the ECM pins using wiring diagrams. Check for short circuits to ground or voltage. Inspect the ground connection quality, as corroded grounds are common culprits in used machinery.

Step 4: Component Replacement and Verification If sensor resistance is out of specification or wiring shows damage, replace the faulty component. For used excavators, always apply dielectric grease to connectors to prevent future corrosion. After repairs, clear the fault code using Sany diagnostic software or a compatible scan tool and perform a test cycle to verify the fix.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sany service manual for your specific model and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with excavator systems.