What is the reason why the Buick ambient temperature always displays -40 degrees?
2 Answers
Buick ambient temperature always displays -40 degrees because the water temperature sensor is damaged or there is a problem with the circuit. Symptoms of a damaged water temperature sensor: When the water temperature sensor fails, it often displays the temperature signal of a hot engine when starting a cold engine. The ECU cannot receive the signal to provide a rich mixture, so it can only supply the engine with a lean mixture (the signal for a hot engine), making it difficult to start the engine when cold. In this case, it is necessary to check whether the water temperature sensor plug is in normal contact or replace the water temperature sensor. Solution: After the vehicle is cold, do not open the radiator cap, remove the sensor, and quickly reinstall it. At this time, there is still vacuum in the pipeline, and there will be no large leakage. For installation positions that are difficult to access (requiring the removal of many components), there is no good method.
I've encountered many Buick owners reporting this issue, usually it's the external temperature sensor malfunctioning. This component is located near the front bumper, responsible for monitoring ambient temperature and transmitting it to the dashboard. If it's open-circuit or short-circuited, the vehicle will default to displaying -40°C as the fault value. I recommend finding a lift or crawling under the car to check if the sensor connector is loose and whether the metal terminals are corroded, as this is the most common cause of poor contact. There could also be wiring issues, such as rodent damage or cracked wire insulation from chassis vibrations. The repair isn't particularly expensive, but remember to disconnect the negative battery terminal before starting work.
