Type: The majority of them use NTC thermistors. Their characteristic is that the resistance decreases as the temperature rises. This enables the ECU to precisely calculate the current temperature by measuring the resistance value of the circuit.
Location: The sensors are usually sewn or adhered to the surface layer and filling layer of the seat cover, very close to the main pressure-bearing areas of the passenger’s buttocks and thighs. This position can most accurately reflect the actual temperature felt by the passenger.
The front and rear seats usually have a separate set of sensors and heating wires each.
In some high-end models, the seat cushion and backrest may each have independent sensors to achieve more precise zone control.
Common faults and symptoms
The sensor itself is quite fragile, and the common causes of failure include:
Physical damage: Frequent getting on and off the vehicle, irregular pressure during riding, or sharp objects may cause the sensor or its cables to be crushed or worn out.
Aging: Long-term exposure to heat and mechanical stress may lead to sensor performance drift or failure.
Moisture/Corrosion: Liquid (such as spilled beverages) seeping into the seat may cause corrosion or short circuit of the sensor connectors or lines.
Fault symptoms:
1. The seat heating completely fails to work: During system self-check, it is found that the sensor signal is lost or abnormal. For safety reasons, the system will be prohibited from starting.
2. The heating cannot be sustained and automatically shuts off: After heating for a few seconds or minutes, it automatically shuts off. This is the most typical symptom of sensor failure. The ECU receives an unreasonable (too high or open circuit) temperature signal, triggering overheating protection.
3. The heating temperature is not controlled: It keeps heating at the maximum power, feeling extremely hot. This may be due to a short circuit in the sensor, giving a continuous “low temperature” error signal, causing the ECU to continuously heat at full power, which is very dangerous.
4. The dashboard displays an error message: On some models, a warning message such as “Seat Heating Fault” may be displayed.
Diagnosis and repair
Diagnosis:
The repair technician will use the diagnostic computer to read the fault codes of the seat heating system.
Using a multimeter, measure the resistance values of the sensors at different temperatures and compare them with the standard values in the repair manual to determine their condition.
Check the connectivity and whether there is any short circuit of the related wiring harness and connectors.
Repair:
It is impossible to replace the sensor alone: In most vehicle models, the temperature sensor, heating wire, and related cables are integrated on a single heating pad. This heating pad is an assembly component and is installed between the seat cover and the sponge filling material.
Replacing the heating pad assembly: Therefore, if the sensor is damaged, usually the entire seat heating pad needs to be replaced. This task has a high labor cost because the seat needs to be completely disassembled (removing the headrest, side cover, removing the seat leather cover, etc.).
Cost: The cost varies greatly depending on the vehicle model and the source of the parts (original factory vs. brand parts). An original factory heating pad may range from several hundred to several thousand yuan RMB, plus several hours of labor cost, the total repair cost may reach over a thousand yuan.
Post time: Nov-13-2025