What are the symptoms of a faulty crankshaft sensor?
3 Answers
The symptoms of a faulty crankshaft sensor are that the engine control unit cannot receive the reference signal during startup, and the ignition coil will not generate high voltage. The function of the crankshaft position sensor is to determine the position of the crankshaft, i.e., the rotation angle of the crankshaft. It is usually installed in the distributor to detect engine speed, crankshaft rotation angle, and to provide signals for controlling ignition and injection, including the top dead center signals for the first cylinder and each cylinder during the compression stroke. There are three main types of crankshaft position sensors: magnetic induction, Hall effect, and photoelectric. The crankshaft position sensor plays a crucial role in the sensor system, as it determines the position of the crankshaft, detects engine speed, and also detects signals such as the top dead center signals for each cylinder used in ignition control and the top dead center signal for the first cylinder used in sequential fuel injection control.
I've fixed quite a few car issues, and the symptoms of a bad crankshaft position sensor are quite noticeable. Initially, the car becomes hard to start—you turn the key for a long time but it won't fire up, the starter cranks but the engine doesn't ignite. Then while driving, the car may suddenly stall, especially at idle or low speeds, like when stopping at a red light, the car shakes violently and then dies. The check engine light on the dashboard stays on, and the trouble code is usually P0335. If ignored, the engine performance will degrade, with poor acceleration, difficulty climbing hills, and even a sharp increase in fuel consumption. Sometimes the car starts fine when cold but develops problems once warmed up, because the sensor fails when hot. It's important to check for loose wiring connections early, confirm with an OBD scanner, and avoid letting it escalate into bigger issues. Replacing the sensor is relatively simple, but ignoring it could damage the coil or ignition system.
I've been driving for over ten years, and once my car suddenly stalled on the highway, which was quite frightening. It turned out to be a faulty crankshaft position sensor. The symptoms started with difficulty starting the engine—it took multiple attempts to get it running. The car ran unevenly, with occasional jerks or vibrations. When accelerating, it felt sluggish and lacked power. The small yellow warning light (check engine light) on the dashboard was on as a reminder. Another time, the car shook violently at idle, feeling like it was about to fall apart. The mechanic explained that a faulty sensor confuses the ECU about ignition timing, directly affecting spark plug operation. Pay attention to these signs—if the car struggles to start, get it checked at a shop promptly to avoid being stranded on the road. It's recommended to regularly maintain and inspect sensor connections, especially in older vehicles prone to such issues.
