What are the symptoms of a faulty water temperature sensor?
3 Answers
The symptoms of a faulty water temperature sensor are: 1. The water temperature gauge needle may stop moving; 2. The water temperature gauge needle may directly point to the highest position; 3. It may also cause inaccurate water temperature detection. Most cars use water-cooled engines, which rely on the continuous circulation of coolant to remove excess heat. Water-cooled engines are equipped with water temperature sensors to monitor the coolant temperature. The function of the water temperature sensor is to convert the coolant temperature into an electrical signal, which is then input into the ECU. This has the following effects: 1. Adjusting the fuel injection quantity—increasing the fuel injection amount at low temperatures; 2. Adjusting the ignition timing—increasing the ignition advance angle at low temperatures and retarding it at high temperatures to prevent knocking; 3. Affecting the idle control valve—the ECU controls the idle control valve based on the water temperature sensor signal at low temperatures to increase the idle speed; 4. Affecting the EGR valve.
Last time I encountered a situation where the coolant temperature gauge was acting erratically, with the needle jumping up and down like crazy or simply stuck at the lowest position. Cold starts were particularly difficult, requiring several seconds of key turning before the engine would reluctantly start. In the summer, when idling at a red light with the AC on, the radiator fan suddenly went into overdrive, making a terrifying noise. It turned out the coolant temperature sensor was faulty, sending inaccurate signals that confused the ECU, leading to erratic fuel injection, skyrocketing fuel consumption, and frequent stalling. The mechanic said a faulty sensor like this could also cause the electric fan to run continuously at high speed, draining the battery dry.
If the coolant temperature sensor is truly broken, the most annoying part is the fan spinning wildly for no reason, and the battery draining rapidly. The engine warning light will most likely illuminate with a yellow indicator, and the onboard diagnostic system will read a fault code showing P0116 series temperature abnormalities. The idle speed will fluctuate erratically, and the car will shake like a sieve when stopped at a red light. During cold starts, black smoke may puff from the exhaust pipe, and fuel consumption can easily increase by two to three liters more than usual. Even worse, driving in hot weather could lead to the cooling system losing control, risking overheating in no time.
