2017~2021 Trunk opening randomly

[CX5_Driver]

The fob is not designed to be a receiver.. but if an unlicensed (over powered) or otherwise nefarious manufactured device cause the fob to "glitch" that is a possibility. FCC regulations state consumer devices must be designed to 'accept' interference (not actively block it), so if the fobs are designed in a manner not yet known to be exploited then this could be a scenario where a Faraday pouch would limit the attack/interference/glitch.

 

[sm1ke]

I was gonna suggest perhaps a faraday pouch for the fob...
https://www.amazon.com/dp/B07GDD35GH/?tag=m20b7-20

not so much another device opening the vehicle; but another device causing the fob to open the vehicle.

This would work, but it defeats the purpose of a key fob. You'd have to remove it from the pouch whenever you wanted to use it.

I've heard of people keeping their key fobs in a faraday box/cage when at home, which prevents the car in the driveway/garage from being "tricked" by thieves boosting or hijacking the signal. You could keep a pouch at work, and instead of walking around with it all day, you could toss the fob in there until it's time to go home.

 

[Avoidin Deer]

Many unlicensed wireless devices use the same frequencies as these key fobs. A stray signal or interference could be the explanation for some of these random activations.

That's an interesting thought.

Tough to confirm.

One could drive a different vehicle for some amount of time while keeping the CX-5 fob far away inside the house. If the doors still opened, then a fob issue could be ruled out. Now it's either errant signals or issues with the vehicle.

 

[CX_FIVER]

This is so strange. Unlike the driver door button, it is necessary to hold down the button to open the rear hatch. Maybe, the hatch was down but not locked when the suv was parked and someone came by, checked it, and voila it was unlocked.

We have 2 hooks next to the front door for truck keys and CX5 keys. Never have to look for them. Makes like alot easier not running around shouting..."You see my keys???" Took me many years to figure it out after hunting for keys frequently.

 

[Ronzuki]

Many unlicensed wireless devices use the same frequencies as these key fobs. A stray signal or interference could be the explanation for some of these random activations.

yep...these FOB cases guarding against unintentional physical activation are not the end-all-be-all solution to this phenomenon. It is very likely stray signals from outside actors (legitimate or not) are the culprits based upon the OP's sequence of events as described. Curious if the OP has remote start capability via cell connection (that so many can't no longer seem to live w/o). Iif so, then the vehicle is wide open to all sorts of nefarious behavior. When was the last time anyone updated their vehicle's malware software or anti-virus software? How 'bout that firewall? Yeah....

I believe the fob is just a transmitter, not also a receiver.

Correct.

I was gonna suggest perhaps a faraday pouch for the fob... not so much another device opening the vehicle; but another device causing the fob to open the vehicle.

Nope. You'd have to put the entire car in a tin-foil pouch, as it contains the receiver, not the FOB.

 

[Retired Boomer]

...You'd have to put the entire car in a tin-foil pouch...

Not so far-fetched.

Plenty of inflatable car covers. Great protection for winter storage.

But AFAIK, no one makes a faraday cage version.

 

[Ronzuki]

haha that's funny...just what I want to do every time I park the car...

Speaking of lack of standards...Gov predictably steps in right on cue:

New US plan keeps autonomous vehicle standards voluntary

The Trump administration on Wednesday unveiled its most recent round of guidelines for autonomous vehicle makers that rely on voluntary standards despite calls for specific...

apnews.com

Absolute disaster in the making. The gov knows even less that the automotive crowd about true automation.

Hellooo...can anyone say Boeing...

 

[mac.mc78]

OKay - so *I* had this issue for the first 2 months of owning my '19 signature, and I went out and bought one of those silicone sleeves on Amazon for our transmitter.

Also, I removed as many keys from the FOB that I absolutely didn't need to have, and I do NOT keep the key in my pocket. When I walk away from the car, I hold the fob in my hand so that it's not possible for anything else to hit the trunk relesae button.

It is 100% the trunk opening button getting pressed by other keys OR by pressing up against something in your pocket. 100%.

I haven't had an issue since.

the button is extremely sensitive.