P15FF00 - P15FF00 Internal Temperature Sensor Fault

P15FF00 Detailed Definition of Internal Temperature Sensor Fault

P15FF00 Diagnostic Trouble Code (Internal Temperature Sensor Fault) is a critical diagnostic parameter in the On-Board Charger (OBC), primarily used to monitor the thermal management status within the onboard charger. The core role of this fault code lies in establishing a closed-loop thermal safety feedback loop. When the control unit continuously monitors key physical node temperature data within the onboard charger, the system performs real-time comparison against preset safety baselines. Once the monitored actual temperature signal exceeds the physical range allowed by the system design, it indicates an increased risk of thermal runaway for the onboard charging module or abnormal sensing feedback, prompting the control system to intervene and execute protection strategies immediately. This mechanism ensures that internal high-temperature environments during high-power electrical conversion processes (such as AC charging or vehicle-to-load discharge) do not cause damage to power devices or the battery system, reflecting multiple safety redundancy designs in the vehicle's electronic electrical architecture.

P15FF00 Common Fault Symptoms

When the onboard charger detects abnormal temperatures and generates this fault code, the vehicle typically enters a restricted operation mode to ensure safety. Specific manifestations that users can perceive include:

• Charging Function Disabled: The vehicle cannot perform AC charging; the charging indicator light extinguishes or displays an abnormal status, even when connected to a charging pile, unable to establish energy transmission.
• V2L Discharge Restricted: If the vehicle has external power supply capabilities, the system may automatically cut off load output to prevent external equipment damage due to insufficient heat dissipation.
• Dashboard Fault Warning: Drivers see related warning information such as "Charging System Fault", "Please Go for Repair" on the central control screen or instrument panel.
• Power Limit Strategy Active: Some models may reduce the maximum output power of the onboard charger to prevent further internal temperature rise.

P15FF00 Core Fault Cause Analysis

Based on system architecture and input data, the fundamental logic of this fault can be summarized into potential anomalies in the following three dimensions:

• Hardware Components: Aging, drift, or failure of the temperature sensor components inside the onboard charger. If the sensor itself cannot accurately collect actual thermosensitive signals around the chip or power devices, it will cause the control unit to receive erroneous low-temperature or high-temperature false alarms.
• Circuits/Connectors (Physical Connection): Although defined as an "internal fault", circuit board traces and heat dissipation module connection points inside the onboard charger may have poor contact or short-circuit risks, leading to localized overheating that cannot be captured by the sensor in time or causing false triggering.
• Controller Logic: Anomalies in the logic operation module inside the onboard charger control unit. This may manifest as a shift in the judgment parameters of fault thresholds, or misidentifying normal transient temperature fluctuations as continuous exceedance during data processing, leading to unnecessary protective shutdowns by the system.

P15FF00 Technical Monitoring and Trigger Logic

The determination of this fault code follows a strict real-time dynamic monitoring process, with its trigger logic primarily consisting of two key steps: status judgment and numerical comparison:

• Monitoring Target: The physical temperature of core power semiconductors, capacitors, and surrounding heat dissipation areas inside the onboard charger ($T_{sensor}$).
• Condition Dependence: Faults are activated only under specific high-load conditions. The system initiates high-frequency monitoring logic only in AC Charging or Vehicle-to-Load states. When the vehicle is stationary and not performing charging or discharging, this fault code usually does not trigger.
• Threshold Judgment Mechanism: The control system continuously reads the temperature sensor signal $T_{sensor}$ and compares it with the maximum allowed temperature $T_{threshold}$ preset by the system. The system determines a fault and stores DTC when the following logical relationship is met: $$ T_{sensor} > T_{threshold} $$ That is, the onboard charger detects that the actual temperature has exceeded the specified threshold. Once this condition is met, the system will immediately generate P15FF00 fault code and execute the protection action of closing the charging interface to prevent hardware thermal damage.