Front Sensors

Posted the same question over in the FB i3 group, but I'll post it here as well.

Does anyone understand how the front parking sensors are meant to operate? It seems essentially random whether they do or do not active upon approaching a stationary object. I've checked the "Auto PDC" setting under "Parking" and yet the sensors still do not engage when I'm creeping toward a parked car. The owner's manual (at p. 114 of the US version) says that the front sensors will engage automatically at less than 2 MPH. That seems really slow to me, and yet the sensors still do not engage at that speed (at least not consistently). We have front sensors on our MB ICE, and they consistently engage at just the right speed (I think under 5mph or so). If the front sensors don't engage in a predictable and consistent fashion, then you might as well not have them. Having had a car with reliable front sensors, we've come to rely upon them when pulling into tight parking spaces, approaching a garage wall, etc. This is a feature that I thought I paid for.

I've seen it suggested elsewhere that the i3 sensors don't come on until you're already deep into the red zone. Is that right, and what would the point of that be? Sure, the sensors on our MB trigger some "false positives" (like pedestrians who walk right in front of the bumper when waiting at a red light), but most of the time it's not bad information to have (like the pedestrians) and I know exactly how the sensors are going to behave when I approach something.

Our experience is that they will not come on until you are within about a foot of an obstacle. That appears really, really close, as the front hood is so short. We had to stop and inch forward with one of us as a safety observer to get it to activate, but sure enough - there was a foot to spare when it first gave warning.

My experience agrees with others. The PDC display and tones automatically activate when the distance between the front bumper and obstacle is at the start of the red zone. To be clear, the sensors are active but the feedback to the driver is not. You can manually engage the system by pressing the P button.

The behavior is different than I've had with prior vehicles that would activate the feedback systems anytime the vehicle dropped below a set speed. In the city, that meant that pedestrians in crosswalks would set off the alarm if you were first at the intersection. The BMW behavior is different but once you're used to it, it's more useful—fewer false alarms—when parking in tight spaces.

My UK car is different.

I've actually (accidentally) driven it slowly into my garage wall to prove it. (Fortunately the rubber bumper (fender) bounced without a mark).

The front sensors only activate automatically with the side sensors - if you get close to the side of another vehicle, wall, toll-booth etc.

If I'm negotiating forwards into a parking space I have to activate them with the button to be safe (even though they're selected as auto).

BMW have told me "that's just the way it is" and other UK users have found the same.

So i did an unscientific test, did not manually activate parking sensors and pulled up to a fence. The front sensors activated just at the end of the orange zone.

I wonder if the behaviour was adjust in the august update.

Surprise! I was in one of our newer roundabouts locally here and the guy ahead of me had slowed, but was still moving as I approached. WHAM the brakes were applied, an indicator alarm sounded and I got the red "too close" warning on the display. It surprised me, and the person behind me who also figured that traffic was MOVING not stopped.

I guess I should dial the detection back to 'medium' rather than 'close' where it was set during delivery walk-through.

Also, the next morning I was headed out of town and about 2 miles out, I got a warning that the front camera was not functioning so I should travel carefully until I could have it checked. So I stopped and examined things--nothing obvious--but close examination found a dried, average-size bug was splatted right on the sensor. I used my thumbnail to scrape it off, returned to the driver seat and went on my way--all fixed!

What puzzled me was that the bug had dried on there, some time ago, but suddenly the system noticed it. Odd?!