What are the reasons for the restricted reversing assist system in the BMW 325Li?

[LorenzoDella]

BMW 325Li reversing assist system restricted reasons are as follows: Camera obstruction: At night, it may cause the camera's view to be blocked, resulting in a "Driving Assist System Restricted" warning. If it's also raining, this situation is more likely to occur. Installing a hidden dashcam, especially a low-end model, may block the light-sensitive camera on the interior rearview mirror. Some installers may also forget to remove the sensor housing inside, leading to this issue. Additionally, a dashcam malfunction or battery drain may trigger the warning. Applying window film or a car wrap may also obstruct the camera's view, causing the warning. The solution is to replace the camera with a new one. Radar abnormality: The radar may be blocked by foreign objects like tree branches, or a license plate frame may obstruct the radar sensor circuit. Deformation of the radar mounting position or a loose radar requires recalibration. The solution is to recalibrate and reinstall the radar.

[SebastianFitz]

Last time I drove my 325Li, I encountered this issue - the central console suddenly displayed a 'assistance restricted' warning while reversing. It had been raining heavily during the drive, and when I got out, I noticed all the rear bumper radar sensors were covered in mud splashes. After cleaning them thoroughly with wet wipes and restarting the car, the problem persisted. At the dealership, they diagnosed it as water ingress causing a short circuit in the left rear radar module, with replacement costing over 2,000 yuan. The technician mentioned that direct high-pressure water jet cleaning on the sensors during car washes often causes this. Now I always avoid spraying water directly on the sensors. Another time during snowy weather, accumulated snow covering the radar triggered an error, but it worked fine after clearing the snow. I’ve also learned to be careful not to bump the sensors when parking, as replacing a single sensor can cost around 800 yuan.

[DiJustin]

I've repaired several 325Li models reporting auxiliary system limitations. A common issue is the trunk wiring harness breaking—when you lift the left rear trim panel, that bundle of wires gets worn down by the metal edge from repeated trunk opening and closing. When testing wire continuity with a multimeter, I found the purple reverse radar signal wire is the most frequently broken. Another car had an issue where the reverse module's power supply was unstable due to incorrect wiring when installing an aftermarket dashcam by tapping into the fuse box. Actually, the system self-check is quite sensitive. Last month, a customer who had just replaced their radar with an aftermarket unit had their functions limited due to protocol mismatch. It's recommended to use OEM protocol-compatible accessories for modifications.

[LaAdrian]

The 325Li's reverse assist limitation is mostly a soft fault. Once, I started the car in an underground garage and got an error, but after driving out and leaving it in the sun for half an hour, it fixed itself—probably due to high humidity causing radar signal drift. Another time, after upgrading the infotainment system, false alarms occurred, and it was only resolved by reinstalling the software version. False system judgments are quite common in daily use: for example, magnetic car stickers on the rear bumper, temporary license plates blocking the sensors, or even modified exhaust tips reflecting signals can trigger it. It's recommended to turn off the engine, lock the car, and wait ten minutes for the system to reset—it might just recover. If repair is necessary, remember to check whether the fault code is C12B1 or C12B2, as they indicate issues with different modules.