DIY - How to Fix the Foot Kick Trunk Open/Release Issue

[torvektheo]

Hello Guys,

As you may or may not know most of our cars come equipped with the foot kick trunk open/release feature as follow:
- 2015 M3 and M4 need to have comfort Access to use this feature
- 2016 and Up are standard with this feature.

After installing a carbon fiber diffuser the feature stops working. On the DIY I explain why this happens and how to fix it. Hopefully this helps someone. Thanks

I know there are threads that may talk about this issue, but a video is always helpful for some folks.

[turbo v6]

Thank you for your post. I just used BimmerCode to disable the kick feature.

»Front Electronic Module« FEM_01, Expert Mode; CAM_SMART_OPENER = nicht_aktiv

[abdulbata]

Thank you. I literally had no idea my car had this feature

[torvektheo]

My pleasure guys!

[adc]

Thank you for the post, I just found out yesterday that my car has this feature, (!!), and I’m contemplating a CF diffuser.

So the simple solution might be to use 2 plastic washers from the hardware store: one between the screw head and metal shield, and another behind the metal shield (between shield and diffuser). This way not only does the screw not touch the metal shield, but the CF diffuser won’t directly touch the shield either.

I’ll try it and report back as soon as I have the new diffuser installed...

[Shadowmak]

I have done the mod today and it works! Thanks alot for sharing it!!!

[torvektheo]

My pleasure guys. Happy to help

[Jbrown7403]

Thanks Theo! The double plastic washer fix worked perfectly!

[SD ///M4]

I just did this fix on my M4 and it worked perfectly! But instead of using the push-in connectors and making plastic washers out of them, I found these nylon washers on Amazon for $11.95 (Prime) and they worked great! (click on the image for the link)



I used the largest washer, put one between the diffuser and the heat shield, and one between the head of the screw and the diffuser, just like adc mentioned. They're thin enough that there's still plenty of purchase for the screw to hold tight. I kicked my foot under the diffuser and it finally worked again!

Edit: In hindsight I realized that I could probably have used a plastic milk jug, cut four round circles the same size as the captive washer, and then just screwed the screw through the middle for the plastic. No cost and just a few minutes of work!

[adc]

Originally Posted by SD ///M4

I just did this fix on my M4 and it worked perfectly! But instead of using the push-in connectors and making plastic washers out of them, I found these nylon washers on Amazon for $11.95 (Prime) and they worked great! (click on the image for the link)



I used the largest washer, put one between the diffuser and the heat shield, and one between the head of the screw and the diffuser, just like adc mentioned. They're thin enough that there's still plenty of purchase for the screw to hold tight. I kicked my foot under the diffuser and it finally worked
again!

Edit: In hindsight I realized that I could have used a plastic milk jug, cut four round circles the same size as the captive washer, and then just screwed the screw through the middle for the plastic. No cost and just a few minutes of work!

Milk jug material may melt, be careful.

[FIN_Nole]

Wow, very interesting and thanks for the info. Clearly a great option to drastically improve the odds for it working when desired.

Out of curiosity, does this also help decrease inadvertent trunk openings (caused by shadows or sometimes just walking by)?

Mine never works when I attempt the 'kick', but randomly I'll park when the sun seems to be at just the right angle and the littlest movement will trigger the sensor when I'm anywhere near the trunk. And then I spend the next minute or two battling with it continuously reopening until I figure out where i can stand to close the trunk without it triggering again. At home i'll just toss the key and close it, but not a great option for a public parking lot (although I probably look pretty stupid either way).

It's ridiculous but I generally walk around the front of the car now just to avoid it altogether...Dealership quoted me $180 to code it off (said they have to charge since they couldn't reproduce the issue).

[torvektheo]

Originally Posted by FIN_Nole

Wow, very interesting and thanks for the info. Clearly a great option to drastically improve the odds for it working when desired.

Out of curiosity, does this also help decrease inadvertent trunk openings (caused by shadows or sometimes just walking by)?

Mine never works when I attempt the 'kick', but randomly I'll park when the sun seems to be at just the right angle and the littlest movement will trigger the sensor when I'm anywhere near the trunk. And then I spend the next minute or two battling with it continuously reopening until I figure out where i can stand to close the trunk without it triggering again. At home i'll just toss the key and close it, but not a great option for a public parking lot (although I probably look pretty stupid either way).

It's ridiculous but I generally walk around the front of the car now just to avoid it altogether...Dealership quoted me $180 to code it off (said they have to charge since they couldn't reproduce the issue).

I do not have this issue, so I cant tell if it will help or not. Wont kill to try

[Kilabyte]

I did this a while back, works most of the time.

The only time it doesn't is when people are watching me.

[HyeM3]

Brother you are a genius I just did this and it works perfectly! Tried 10 times in a row and it worked every single time

Disclaimer for everyone: in order for the kick feature to work you have to touch your foot against the diffuser (at least for me) so be careful not to burn your foot on the exhaust

[SD ///M4]

Originally Posted by FIN_Nole

Wow, very interesting and thanks for the info. Clearly a great option to drastically improve the odds for it working when desired.

Out of curiosity, does this also help decrease inadvertent trunk openings (caused by shadows or sometimes just walking by)?

Mine never works when I attempt the 'kick', but randomly I'll park when the sun seems to be at just the right angle and the littlest movement will trigger the sensor when I'm anywhere near the trunk. And then I spend the next minute or two battling with it continuously reopening until I figure out where i can stand to close the trunk without it triggering again. At home i'll just toss the key and close it, but not a great option for a public parking lot (although I probably look pretty stupid either way).

It's ridiculous but I generally walk around the front of the car now just to avoid it altogether...Dealership quoted me $180 to code it off (said they have to charge since they couldn't reproduce the issue).

Do you have the BMW M Performance Carbon Fiber Rear Diffuser? If your trunk opens randomly it seems unlikely that you have this diffuser because it's rare that the kick-to-open feature works correctly after installing the diffuser. I literally have never had the trunk open inadvertently due to proximity since I installed the diffuser. Some aftermarket "carbon fiber" diffusers don't cause this problem because the material is not actually carbon fiber.

This fix works because it insulates the CF diffuser from the metal heat shield. If you don't have this diffuser this fix wouldn't make any difference in the way yours works because the stock piece is plastic.

Are you sure it's not because the button on your key fob is getting pushed while in your pocket?

[FIN_Nole]

Originally Posted by SD ///M4

Do you have the BMW M Performance Carbon Fiber Rear Diffuser? If your trunk opens randomly it seems unlikely that you have this diffuser because it's rare that the kick-to-open feature works correctly after installing the diffuser. I literally have never had the trunk open inadvertently due to proximity since I installed the diffuser. Some aftermarket "carbon fiber" diffusers don't cause this problem because the material is not actually carbon fiber.

This fix works because it insulates the CF diffuser from the metal heat shield. If you don't have this diffuser this fix wouldn't make any difference in the way yours works because the stock piece is plastic.

Are you sure it's not because the button on your key fob is getting pushed while in your pocket?

Originally Posted by SD ///M4

Do you have the BMW M Performance Carbon Fiber Rear Diffuser? If your trunk opens randomly it seems unlikely that you have this diffuser because it's rare that the kick-to-open feature works correctly after installing the diffuser. I literally have never had the trunk open inadvertently due to proximity since I installed the diffuser. Some aftermarket "carbon fiber" diffusers don't cause this problem because the material is not actually carbon fiber.

This fix works because it insulates the CF diffuser from the metal heat shield. If you don't have this diffuser this fix wouldn't make any difference in the way yours works because the stock piece is plastic.

Are you sure it's not because the button on your key fob is getting pushed while in your pocket?

Yeah, M Performance diffuser straight from the factory and it's not the key fob button. I probably shouldn't have said 'randomly'. The cause for the trigger is definitely shadow related and very difficult to replicate. But when it does happen, it's a major pain. I walk past, it triggers, I close the trunk, then immediately after closing it triggers again. Have repeated that process 15+ times in a single sitting before either flipping the lock switch in the glove box, getting my key fob further away before closing, or finding a lucky spot where I can stand and close it without re-triggering.

Seriously, nobody else has had this happen? It's my one and only complaint I've ever had about this car.

[sappersix]

Thanks Theo. I did this a few weeks ago and so far so good.

All I had lying around were some rubber garden hose washers, so I grabbed four and put two on each side (one between fastener and diffuser and another between diffuser and metal sheet).

Kick-to-open now works 9 out of 10 times. Also, I no longer have the mysterious unintended trunk lid opening situation (at least so far).

Originally Posted by FIN_Nole

Seriously, nobody else has had this happen? It's my one and only complaint I've ever had about this car.

I'm in the same situation. Official BMW M Carbon Fiber Diffuser. Kick-to-Open stopped working and I would have random trunk openings. Reading your description, I completely have been there. This *seems* to have stopped it; time will tell.

[CarbonAlpine]

Originally Posted by FIN_Nole

Yeah, M Performance diffuser straight from the factory and it's not the key fob button. I probably shouldn't have said 'randomly'. The cause for the trigger is definitely shadow related and very difficult to replicate. But when it does happen, it's a major pain. I walk past, it triggers, I close the trunk, then immediately after closing it triggers again. Have repeated that process 15+ times in a single sitting before either flipping the lock switch in the glove box, getting my key fob further away before closing, or finding a lucky spot where I can stand and close it without re-triggering.

Seriously, nobody else has had this happen? It's my one and only complaint I've ever had about this car.

I have the exact same issue, once it opened 5 times back to back with me pumping gas next to it. I looked like I kidnapped someone and they were pulling the release inside the trunk. I kept shutting the trunk and by the last time I slammed it, it gets annoying. I'm pretty sure the cops were called or I was being video recorded, but that's the world we live in now.

[RJV3]

I took my car to the dealership after noticing my PDC sensors were acting up after it rained and would cut out. I have an m sport rear and front bumper (non oem) and was purchased through kies motorsports. I have the diffuser color matched since I don't really like the carbon fiber or matte Grey look from OEM bumper and diffuser combo. The dealer replaced the PDC harness. But also the fact my bumper is not oem was clear as day. The upper sensor was held to the middle of the car frame by screws and the lower sensor also. I ordered the correct oem plastic bracket that the sensors are to be mounted too. Dealer called me and confirmed the car was fixed and ready to pick. When I got there today, I tried the kick release for the trunk and it did not work. Understanding that some materials like the carbon fiber diffuser blocks the signal. But this non oem bumper is of the same poly propelene materials as the OEM. It's using the OEM bracket to hold both sensors. Not sure why it's not working now. I took the key fob and Swiped it under the sensor as of it was my foot and the trunk release worked. Holding the key and using my foot, it doesn't work. The technician is going to look at the car again I. The morning. I recommended trying to use the rubber washer trick. Hoping that works for me. Otherwise I just spent another grand replacing a harness and buying a bracket plus labor for nothing.

[Zomboss]

I installed a M Performance diffuser yesterday, and I wasn’t able to get the kick trunk feature to work even with the nylon washer mod. I was able to isolate to the screw holding the diffuser to the heat shield on the passenger side. Even with two nylon washers separating the screw head to the diffuser and the diffuser to the heat shield, I think the screw thread is still making contact between the CF diffuser and the heat shield. After numerous attempts to adjust the screw and washers, I gave up. I’ll try replacing that screw with a zip tie next.

[zamboni]

Originally Posted by Zomboss

I installed a M Performance diffuser yesterday, and I wasn’t able to get the kick trunk feature to work even with the nylon washer mod. I was able to isolate to the screw holding the diffuser to the heat shield on the passenger side. Even with two nylon washers separating the screw head to the diffuser and the diffuser to the heat shield, I think the screw thread is still making contact between the CF diffuser and the heat shield. After numerous attempts to adjust the screw and washers, I gave up. I’ll try replacing that screw with a zip tie next.

Were you able to get it to work? My worked occasional not all the time wonder anyone can recommend which hardware to purchase and able to make it work.
Thanks

[zamboni]

Originally Posted by SD ///M4

Do you have the BMW M Performance Carbon Fiber Rear Diffuser? If your trunk opens randomly it seems unlikely that you have this diffuser because it's rare that the kick-to-open feature works correctly after installing the diffuser. I literally have never had the trunk open inadvertently due to proximity since I installed the diffuser. Some aftermarket "carbon fiber" diffusers don't cause this problem because the material is not actually carbon fiber.

This fix works because it insulates the CF diffuser from the metal heat shield. If you don't have this diffuser this fix wouldn't make any difference in the way yours works because the stock piece is plastic.

Are you sure it's not because the button on your key fob is getting pushed while in your pocket?

Hello SDM4,

I recently upgraded to the performance diffuser and the motion worked randomly please share the hardware you had used to install on your M4.

TIA