What is Sany Excavator Fault Code P107?

Fault Code P107 indicates a malfunction in the engine coolant temperature (ECT) sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) receives voltage readings outside the expected range from the coolant temperature sensor, typically above 4.8-4.9 volts for most Sany excavator models.

The ECT sensor plays a critical role in engine management by monitoring coolant temperature and sending real-time data to the ECM. This information directly influences fuel injection timing, idle speed adjustment, and cooling fan operation. When P107 activates, the ECM loses accurate temperature data, forcing the system into a default "limp mode" that can significantly impact machine performance and fuel efficiency. For used Sany excavators, this code often signals age-related sensor degradation or wiring harness issues common in machines with 5,000+ operating hours.

Common Symptoms

• Check Engine Light or malfunction indicator illuminated on the dashboard display
• Engine runs in cold start mode continuously, causing rough idle and black smoke from exhaust
• Cooling fan runs at maximum speed constantly, regardless of actual engine temperature
• Difficulty starting the engine when warm, or extended cranking times
• Noticeable power derate or loss of hydraulic responsiveness during operation

Potential Causes

The most frequent causes of Code P107 in used Sany excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing near the engine block mounting points
• Failed coolant temperature sensor due to internal element corrosion or thermal cycling damage
• Corroded or loose connector pins at the sensor plug (common in machines exposed to muddy or wet conditions)
• Damaged ECM wiring between the sensor and control module, particularly at harness flex points
• Short circuit to battery voltage caused by damaged insulation rubbing against metal surfaces
• Faulty ECM (rare, but possible in older machines with electrical system history)

How to Troubleshoot and Fix Code P107

Step 1: Visual Inspection Begin with a thorough inspection of the ECT sensor and its wiring harness. Located typically on the engine block near the thermostat housing, check for physical damage, coolant leaks, or corrosion on the two-wire connector. For used excavators, pay special attention to harness routing where wires contact engine components—this is a common wear point.

Step 2: Electrical Testing Disconnect the ECT sensor connector and use a digital multimeter to measure resistance across the sensor terminals. At room temperature (68°F/20°C), you should read approximately 2,000-3,000 ohms. Compare your readings against Sany's specification chart. Next, check for continuity in the wiring from sensor to ECM and verify no shorts to ground or voltage.

Step 3: Voltage Circuit 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 reads near battery voltage (12V+) or zero, the problem lies in the wiring harness or ECM itself.

Step 4: Component Replacement If the sensor tests faulty, replace it with a genuine Sany or OEM-equivalent ECT sensor using proper thread sealant. For used machines, always replace the connector pigtail if corrosion is present. After replacement, clear codes using Sany diagnostic software or a compatible scan tool and verify proper operation through a complete heat cycle.

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Disclaimer: This guide provides general troubleshooting information. Always consult your Sany service manual and consider professional diagnostic assistance for complex electrical issues, especially when working with used equipment that may have undocumented modifications or repairs.