Hi, did this job today as the warning was bugging me. The manual worship advises to remove full bumper. I tried to work around it but it’s not possible. I did the top only method attempting to access the kidney grille and reach under it… no chance.

The way the bumper works is that there is the pedestrian safety system behind a big piece of what looks like styrofoam. You can’t reach anything without removing the bumper.

All in took me about 3 hours. I did not replace the sensor. I was just curious. The sensor was fixed after the work. I went round all 4 and cleaned the contacts and lubed with silicone spray.

To remove the bumper you will need to disconnect the sensors main loom, it’s ok the right side and can be quite dirty. I cleaned that too as I saw a little surface corrosion on contacts. If you have headlight washers that will need disconnected too. It will drip all the liquid so have something to catch or just waste.

You can access the sensors once you unhook the bumper and kind of pull it but leave it hanging on the edge. Personally, at that point you might as well take it off and clean the sensors properly.

For me this fixed the issue. The sensor seemed to have rock chips on it so I assumed it was definitely gone. Until after two weeks it worked randomly. Then I noticed it works straight after starting the car and then stops within a minute and gives the park unaided error.

For what it’s worth, and I assume you know that, I diagnosed the broken sensor by engaging PDC and touching/listening to each sensor. They vibrate if working. The front right bellow the plate was the culprit. As I say, it seems it was not broken, just a connection issues.

Inspect the whole loom when bumper is off. I found a section on mine where the outside insulation had worn off/split. The wires were good thankfully, repaired with electrical tape.

Overall easy job, the 8mm nuts are all identical and work quite well. Nothing stripped. The two screws on each side hold the side of the bumper, they were harder to remove but still easy.

When removing the arch liner be careful with the side where it’s near the brake/ABS lines. Same when reinstalling. The air tunnel too, it has a lip on it which goes to “click” in the arch liner. Be wary to get it in place correctly.

Overall, silly for a sensor connection to fail but the bumper is actually well put together and easy to remove without damaging anything.

Take your time and test in situ, you might get errors but they will disappear. No coding required. By in situ I mean, don’t be afraid to get the ignition on and press PDC button with car in the air and bumper hanging off.

This was all on an F22, 240i to be exact. Yours will be very similar I imagine. Good luck.

 

Btw, this post of mine deserves an edit for anyone that finds this in the future.

The aforementioned procedure did not fix the issue. It was only temporarily, whilst YMMV, for me it lasted 3 days. And sure enough, the bong was back.

I should interject that BMW have taken a family retarded stance on dealing with this issue. Whilst I can see legal reasons playing a role, turning off all sensors when only one is broken is both stupid and revenue generating. You can now charge more and pretend real diagnostic is going on. On older models I have seen the case where one sensor will simply show all red or just not detect anything. The other sensors still work and provide some guidance. Further, every time you put the car in R, it displays a warning message covering your camera that you need to manually dismiss. Overall, not a smart approach.

ISTA will display the exact sensor that’s the issue. However that’s debatable as on mine it has a historic code for a “middle sensor” i.e. it thought the car had 6 sensors. It only has 4.

The OEM sensor is £118 odd, aftermarket is between £10-30. You decide what your time is worth, in previous cars I’ve had serious issues with aftermarket sensors particularly ABS ones. I’m not saying go OEM but don’t go cheapest either. Middle ground was fine. Whilst at it, zip tie a mesh off eBay on the grills. It will help stones and other debris.

Overall, easy repair as long as you take your time and are careful. And don’t listen to online advice, including me, that a sensor might work just with cleaning. It might, but you’re better having a spare there in case it doesn’t.

Best of luck.