What are the symptoms of a faulty steering gear in a BMW 5 Series?

[Lawrence]

When driving, strong vibrations in the steering wheel, unstable direction, increased free play, understeer or oversteer indicate a malfunction in the steering gear. Here are the specific symptoms of a damaged steering gear: Difficulty in steering wheel return: Generally, vehicle steering wheels have an automatic return function. For cars equipped with hydraulic power steering gears, the automatic return function is somewhat weakened due to hydraulic damping. However, if the return speed is too slow, it indicates a fault in the return function. This type of fault usually occurs in the mechanical part of the steering system. Steering wheel shaking or deviation: When driving on one side of a cambered road, the car naturally tends to deviate. If the camber is significant, the deviation becomes more noticeable due to external factors. After ruling out tire pressure issues, the cause is often a loosened or broken mechanical component in the steering gear.

[Cunha]

I've been repairing cars for over a decade, and it's quite common to see BMW 5 Series steering gear failures. The most obvious symptom is a clunking noise when turning the steering wheel, especially during stationary turns which can be particularly harsh. Sometimes the steering suddenly becomes heavy, like trying to bend an iron block, making driving extremely strenuous. Some owners report increased steering play, where the wheels don't respond even after turning the wheel a quarter turn. The most dangerous issue is steering stickiness - when making minor adjustments at highway speeds, it feels glued in place, then suddenly jerks when forced, which is terrifying! I recommend first checking the tie rod ball joints. If the rubber boot is torn and allows dirt ingress, the entire steering gear will fail quickly.

[VanDaniela]

Last week, my best friend's 530Li had the same issue! When dropping off the kids in the morning, she noticed squeaky rubber friction sounds when turning the steering wheel, and the steering wheel would shake when making turns in the parking lot. It got even more embarrassing at noon when taking clients to lunch—during a U-turn, the power steering would intermittently fail, almost causing her to scrape a roadside post. At the dealership, they diagnosed it as a failed sensor inside the steering gear and ended up replacing the entire assembly for over 8,000 RMB. Actually, catching it early could have saved money—for example, being alert if the power steering fluid turns black and foamy, or replacing the tie-rod dust cover immediately if it cracks.

[StIker]

From a mechanical perspective, BMW 5 Series steering gear failures progress through three stages: In the initial phase, overheating of the electric power assist motor triggers protection, resulting in heavier steering that can be restored by turning off and restarting the engine. In the intermediate stage, gear set wear leads to reduced steering precision, manifesting as uneven steering force between left and right turns. In the final stage of complete failure, the dashboard illuminates the steering fault light, and the steering wheel may even lock up. Special attention should be paid to high-end models with active steering—damage to the planetary gear set produces a clicking sound from gear meshing. It is recommended to use a diagnostic scanner to check the steering angle sensor data stream; a deviation exceeding 5% requires immediate inspection and repair.