What are the symptoms of a faulty knock sensor?
4 Answers
The symptoms of a faulty knock sensor are: 1. It will reduce the engine power; 2. The engine will produce a knocking sound; 3. It may damage the engine pistons and cylinder block; 4. It cannot detect engine knock signals; 5. It cannot automatically retard the ignition timing; 6. The engine warning light on the dashboard will illuminate. The knock sensor is a sensor that detects engine knock. A sensor is a detection device that can sense the measured information and convert the sensed information into electrical signals or other required forms of information output according to certain rules, to meet the requirements of information transmission, processing, storage, display, recording, and control.
If the knock sensor is faulty, I can tell you from experience that common symptoms include the sudden illumination of the engine warning light, a noticeable drop in the car's power, difficulty accelerating when pressing the gas pedal, and a feeling that the entire vehicle is being held back. You'll notice the engine shaking violently, especially during acceleration, as if it's struggling and wobbling, sometimes accompanied by a metallic rattling sound, which is a sign of internal engine knocking. Fuel consumption will skyrocket—my regular customers have mentioned that a full tank of gas runs out in just a few days because the system can't properly adjust the combustion state. Other issues include difficulty starting the engine when cold or unstable idling, where the car may even tremble when stopped at a red light. If not addressed promptly, knocking can damage the pistons or cylinder walls, leading to costly repairs. I recommend checking the trouble codes with an OBD scanner as soon as these signs appear. In most cases, replacing the sensor will solve the problem, but delaying repairs increases the risk of major engine damage.
I was driving my old car on the highway when suddenly it felt like the car couldn't move anymore. Even with the accelerator pedal floored, there was no power, and the engine light on the dashboard came on, which really startled me. Later, the mechanic told me the knock sensor was broken, and that's when I understood the symptoms: weakened power during daily driving, and the car would jerk like going over mountain roads when accelerating. Fuel consumption also skyrocketed—I used to fill up once a month, but now I have to do it every two weeks, which has significantly increased my expenses. The most annoying part was the strange noises; the engine made clattering sounds, especially when climbing hills or under heavy load, making me worry the car was about to fall apart. There was also one time when starting the car, it took a long time to turn over, and this was more noticeable when the engine was cold. Fortunately, it didn't cause any major issues, and after replacing the sensor promptly, everything returned to normal. If you experience these symptoms while driving, don't delay—check the trouble codes immediately. Safety comes first.
When driving, I always pay attention to small details. If the knock sensor is faulty, obvious symptoms include the check engine light coming on followed by the car becoming unstable. You'll feel noticeable shaking and vibrations during acceleration, and the engine noise increases, resembling slight explosions. Fuel consumption also rises quickly, costing hundreds more per month on gas. The biggest concern is the safety risk—delaying repairs may cause internal engine damage, making long trips feel unsafe. Last time I heard unusual noises, I got it checked immediately, and after the repair, everything was smooth again. A reminder to everyone: don't ignore these small warning signs.
