What are the symptoms of a faulty BMW eccentric shaft sensor?
2 Answers
BMW eccentric shaft sensor failure can cause the car to fail to start. The criteria for judging bearing damage mainly depend on two manifestations: vibration and temperature. Vibration of eccentric bearings: Bearing vibration is highly sensitive to bearing damage, such as spalling, indentations, rust, cracks, and wear, all of which can be reflected in bearing vibration measurements. Therefore, by using special bearing vibration measuring devices (such as frequency analyzers), the magnitude of vibration can be measured, and the specific abnormality can be inferred from the frequency distribution. The measured values vary depending on the bearing's operating conditions or the sensor installation position, so it is necessary to analyze and compare the measurement values of each machine in advance to determine the judgment criteria. Temperature of eccentric bearings: The temperature of eccentric bearings can generally be inferred from the temperature outside the bearing housing. If the outer ring temperature can be directly measured using an oil hole, it is even more suitable. Typically, the temperature of eccentric bearings gradually rises as the bearing begins to operate and stabilizes after 1-2 hours. The normal temperature of the bearing varies depending on the machine's heat capacity, heat dissipation, speed, and load. If lubrication or installation is improper, the bearing temperature will rise sharply, leading to abnormally high temperatures. In such cases, operation must be stopped, and necessary preventive measures must be taken. Using thermal sensors, the working temperature of the bearing can be monitored at all times, and automatic alarms or shutdowns can be implemented when the temperature exceeds the specified value to prevent bearing seizure accidents.
As a mechanical enthusiast who often helps friends with car repairs, I've noticed some distinctive symptoms when the BMW eccentric shaft sensor fails. The most common sign is the sudden appearance of the yellow drivetrain malfunction light on the dashboard, sometimes accompanied by the engine warning light. It's particularly noticeable during cold starts - the engine will surge like it's having asthma, with the tachometer needle shaking like a phone on vibrate mode. Once while accelerating on the ring road, I clearly felt the power delivery becoming intermittent when pressing the throttle, as if someone suddenly took away half the accelerator. At traffic lights it was even more dramatic - the whole cabin shook with the RPM fluctuating wildly, almost making me think the engine would stall. My advice: don't push it. Get the fault codes read with a diagnostic scanner immediately - most cases show eccentric shaft-related codes like 2A87/2A82. Early repair can prevent stepper motor damage.
