What are the reasons for a car speedometer not working?
2 Answers
There are two scenarios when the speedometer stops working. One is when it stays at 0, which usually indicates a broken display or a short circuit. The other scenario is when it stays at the maximum point, commonly referred to as "pegging the needle," and it can be reset. If the speedometer stays at 0 and the odometer also stops moving, there is a high probability that the speed sensor is faulty, or there might be an issue with the wiring between the sensor and the instrument cluster. This is a minor problem that can be fixed by a repair shop. First, check if the flexible shaft connection is broken, and then observe if the odometer numbers increase while driving. If they do, it means the speedometer is not working. In this case, there is no need for further repairs; simply replace it with a new one. Whenever the car is moving, the gears inside the speedometer are rotating. Over time, these gears, which are made of plastic, wear out. Replacing them is not expensive. The speedometer is typically located inside the instrument panel, symmetrically placed alongside the speed and odometer. It operates based on magnetic principles, receiving pulse signals generated when the primary current in the ignition coil is interrupted and converting these signals into a displayable speed value.
I encountered the issue of a non-functioning speedometer last year, which forced me to rely on my phone's navigation for speed readings while driving—quite dangerous. There are several common causes: First, a faulty wheel speed sensor, where the sensor near the wheel is either dirty or damaged, preventing data from reaching the dashboard. Second, the dashboard itself might be malfunctioning, such as due to a short circuit on the circuit board. Third, aging wires or loose connectors, especially on bumpy roads, can exacerbate the problem. I also researched and found that many modern vehicles rely on electronic controls, so software bugs or ECU malfunctions could also cause this issue. During regular maintenance, it's good to pay attention to the cleanliness of the wheel speed sensors. If you notice the needle isn't moving before driving, it's best to avoid high speeds and visit a repair shop to check the fuses and sensors—it won't take much time to fix. Safety should always come first; don't wait for an accident to regret it.
