MarkH
Posts: 69
Joined: Mon Jun 10, 2019 1:17 pm

Replace rear parking sensor

Tue Oct 22, 2019 12:30 pm

I have a replacement sensor arriving from AliExpress next week.
Before I'm ready to tackle this job I want to know exactly how I go about removing the old sensor from the bumper (and fixing the replacement in place).
Has anyone done this and can offer some advice, please?

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MKH
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Joined: Fri Nov 02, 2018 5:48 am
Location: Dallas

Re: Replace rear parking sensor

Tue Oct 22, 2019 12:55 pm

You will need to take off the bumper fascia to get at the back side. Showed pretty clearly in this video.

https://www.youtube.com/watch?v=tc4jgJuXbIM
Sensor.jpg
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Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

MarkH
Posts: 69
Joined: Mon Jun 10, 2019 1:17 pm

Re: Replace rear parking sensor

Tue Oct 22, 2019 4:57 pm

Thanks Mark.
Yeah, I've already had the bumper off (installing the EcoHitch!) so I know about that.
The other pic I've seen too, but the sensor is not the same as the i3 so the method of removal is not the same.

It may be apparent how to get it out, once I open it up again, but I just want to make sure I don't end up having to reassemble things without having managed to replace the sensor.

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MKH
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Location: Dallas

Re: Replace rear parking sensor

Wed Oct 23, 2019 1:21 pm

Took me a while to find it - not logically listed in the repair guide.
Rear Sensor01.jpg
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Rear Sensor02.jpg
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Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

MarkH
Posts: 69
Joined: Mon Jun 10, 2019 1:17 pm

Re: Replace rear parking sensor

Wed Oct 23, 2019 8:51 pm

This is the unit that I've ordered. The part number is 66209274427 01, which I think is correct for the i3
https://www.aliexpress.com/item/3270531 ... 5c4eZfQZM6

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MKH
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Location: Dallas

Re: Replace rear parking sensor

Fri Oct 25, 2019 7:04 am

That is the right sensor according to the part number. Looks like the design may have changed slightly from the picture in the repair guide. Instead of the plug receptacle offset and then straight inline with the sensor head, it now is at 90 degrees - maybe for better clearance.
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 19 inch 427 wheels, EVoInnovate EVSE

MarkH
Posts: 69
Joined: Mon Jun 10, 2019 1:17 pm

Re: Replace rear parking sensor

Fri Oct 25, 2019 8:26 pm

Yeah, it arrived today so I'll try to install it some time in the next week.
Let you know how I get on (and if it works - NZ12.85 compared to NZ$295 seems too good to be true. But I figure it's cheap enough to give it a go.)

MarkH
Posts: 69
Joined: Mon Jun 10, 2019 1:17 pm

Re: Replace rear parking sensor

Thu Oct 31, 2019 2:25 pm

I said I'd send an update - and now I don't want to, because it's confusing :?

I had been enduring this problem (one rear sensor erroneously triggering) consistently for the past 3 months.

Before swapping out the faulty sensor for the new (cheap) one, I did some checking:
- I disconnected the faulty sensor and ignited the car - "Auto PDC failure"
- I reconnect the faulty sensor - it triggers again (with no failure message).
- I swapped sensor 1 and sensor 2 (by position) and the faulty triggering moved accordingly (with the sensor).
- I replace the faulty sensor (in its new position) with the new one - "Auto PDC failure"
- I replace the new sensor with the old faulty sensor (in its new position) - that sensor is now fine but the one that has been moved to the original faulty position is now triggering. (go figure)

In the course of doing all this, I used contact clean on all the joints.

So, at that point, I concluded that :
a) the new cheap sensor doesn't work.
b) the original triggering might have been caused by a wiring problem at that sensor position (but the problem moved when I moved the sensor?).

I decided to bite the bullet and get it fixed professionally.

NEXT day.

When I backed out of the garage - SILENCE!!!
No failure message - everything working as it should :-)

I would like to again test the new cheap sensor (just to be sure it is no good - and I can leave appropriate feedback) but am reluctant to disturb things.

I have discovered that it is possible to replace any of these sensors without having to remove the whole bumper. By undoing 2-3 bolts along the bottom of the shirt, you can get your hand in to unplug the cables. The sensor fits into a plastic seat that has two long flexible posts that run up either side of the barrel of the sensor. To release the sensor, pry these away from the sensor barrel to release the retaining clips. Press the sensor from the outside and it slips out easily.

WillKeogh
Posts: 1
Joined: Mon May 10, 2021 2:25 pm

Re: Replace rear parking sensor

Mon May 10, 2021 2:29 pm

All of the rear sensors on my i3 were corroded, with paint bubbling, and frequent false alarms when reversing. BMW said this was not covered by the warranty and wanted £600 to fix. Grrrr.
With the car out of warranty I decided to replace these sensors myself, but then with one in my hand it occurred to me to try just sanding off the flaking paint and corrosion and repaint the surface. And it has worked - all 4 sensors now working correctly and no more false alarms. It has been good for several weeks in a wide range of weather.
That ecohitch video was very helpful. It would have taken me a while to find that bolt behind the number plate.

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