日产曲轴位置传感器A29-660，替代23731-6J90B/AL61A，引擎转速监测。

If your Nissan experiences starting difficulty, weak acceleration, or intermittent engine stalling with the check engine light and crankshaft position sensor fault codes, the original sensor is aging or failing. This sensor monitors crankshaft speed and position in real time and sends signals to the ECU to control ignition timing and fuel injection; core engine component. OEM number A29-660; can replace OEM 23731-6J90B and AL61A; fits Nissan models with HR/MR engines (e.g., Sylphy, Tiida, Sunny). Installation: disconnect negative battery, clean mounting hole, apply small amount of lubricant; ensure clearance between sensor and flywheel ring gear is 0.5-1.5 mm; tighten to 8-10 N·m to avoid housing deformation.