What are the symptoms of a faulty coolant temperature sensor?
2 Answers
The symptoms of a faulty coolant temperature sensor are: 1. The coolant temperature gauge needle does not move; 2. Increased fuel consumption and unstable idle speed; 3. Difficulty in acceleration and the engine speed cannot rise; 4. Difficulty in starting the engine when cold, and the temperature signal still shows as hot when starting the engine cold. If these symptoms occur, it is necessary to check whether the coolant temperature sensor plug is in proper contact or replace the coolant temperature sensor. The functions of the coolant temperature sensor: 1. Adjust the fuel injection quantity, increasing the fuel injection when the temperature is low; 2. Adjust the ignition timing, increasing the ignition timing when the temperature is low, and delaying the timing when the temperature is high to prevent detonation; 3. The ECU controls the idle speed control valve based on the coolant temperature sensor signal when the temperature is low.
Last time I drove my friend's old Buick, the coolant temperature sensor failed. Cold starts were particularly difficult, requiring multiple attempts to ignite, and the idle speed fluctuated erratically, like it was having a fit. After driving for twenty minutes, I glanced at the dashboard and was shocked: the temperature needle was stuck at the lowest position, but in reality, the engine cover was scorching to the touch. When I turned on the AC, the fan didn’t spin at all, and fuel consumption shot up by 30%. The worst part was the sluggish acceleration—even flooring the throttle couldn’t muster enough power to overtake a big truck. At the repair shop, the diagnostic codes confirmed the sensor was sending faulty signals, preventing the fan from cooling the engine when it should, nearly roasting it.
