What are the symptoms of a bad engine speed sensor?
2 Answers
Speed sensors are usually installed in the distributor or engine, and they can detect the rotation angle of the crankshaft. Once a fault occurs, it can disrupt the operation of the ignition system, causing the engine to fail. Since most speed sensors are magnetic pulse type, they can emit weak electrical signals, which can be detected using a multimeter or oscilloscope. The symptoms of a bad engine speed sensor are as follows: 1. Unstable engine idle. 2. Momentary stalling or engine shutdown when starting the vehicle or decelerating to a stop. 3. Decreased engine acceleration performance. 4. Deviation in the speed display on the dashboard. 5. The engine fault light comes on.
My old car has been running for over a decade, and I've experienced sensor failures before. If the crankshaft position sensor fails, starting the car becomes extremely difficult - sometimes it takes forever to turn over. At idle, the engine shakes violently as if it's about to fall apart, and there's no power when accelerating, especially noticeable when climbing hills. That yellow warning light on the dashboard will definitely illuminate, alerting you to system faults. Even worse, the engine might suddenly stall while driving, which is downright dangerous. Fuel consumption will also spike dramatically - a normally fuel-efficient car might burn an extra liter of gas. The root cause is usually lost sensor signals, preventing the ECU from properly controlling ignition timing or fuel injection. My advice: don't delay - take it to a professional repair shop immediately for sensor replacement. It typically costs just a few hundred yuan to fix, and prompt replacement prevents damage to other components while ensuring long-term driving safety.
