CX-90 Blind Spot Monitor Malfunction

[ccspeedsix]

Had the false positive trigger an emergency braking when backing out of a parking spot in a parking lot this weekend. Driver side was the "closer" corner to the row of cars behind me, absolutely no movement what so ever.

I will say that the system did also work well with some people who walked by on the far side of the aisle from my car, I was surprised it detected that at all.

Had a CEL pop up this AM, so ill be taking the car in sooner than anticipated and will be bringing up the BSM. I have been taking videos and what not to show the issue.

 

[RhodiumRay]

Just throwing this out there as a possible reason on the BSM. I have read on other forums that the Pulse aftermarket safety system being installed by the dealer on some CX90’s is causing issues according to Mazda corporate. Unsure if your dealer installed it on the car you have.

 

[MikeATL]

Just throwing this out there as a possible reason on the BSM. I have read on other forums that the Pulse aftermarket safety system being installed by the dealer on some CX90’s is causing issues according to Mazda corporate. Unsure if your dealer installed it on the car you have.

I'm pretty sure my CX90 does not have the Pulse Safety System.

The Mazda Customer Experience Center case manager we talked to would only admit to having heard of this issue from one other CX90 owner she have talked to so far.

 

[ccspeedsix]

Ironically, after three days the dealer reported they couldnt replicate the issue with the BSM (I think what this means it wasn't throwing any BSM specific error codes), but the video proof (many videos) I guess forced them to go ahead and get both rear BSM modules ordered for replacement. I dont know how they couldnt replicate it in 60 miles of driving, when I have had multiple drive cycles where it occurred since I got my car back, but hopefully the new sensors fix the issue.

CEL ended up being the secondary O2 sensor, which just needed a re-calibration apparently...

 

[MikeATL]

Ironically, after three days the dealer reported they couldnt replicate the issue with the BSM (I think what this means it wasn't throwing any BSM specific error codes), but the video proof (many videos) I guess forced them to go ahead and get both rear BSM modules ordered for replacement. I dont know how they couldnt replicate it in 60 miles of driving, when I have had multiple drive cycles where it occurred since I got my car back, but hopefully the new sensors fix the issue.

CEL ended up being the secondary O2 sensor, which just needed a re-calibration apparently...

They kept your car for 3 days and drove 60 miles for the BSM and CEL issues? Did you a least get a nice loaner car while they have yours?

I still have not gone in for the BSM issue, because I figure I'll wait for my Premier Tow Package to come in before visiting the service department. Waiting over a month so far for my Hitch to become available from Mazda is another problem I'm having.

Please keep us posted on weather or not new BSM modules fix the issues.

 

[ccspeedsix]

It was primarily me giving them the chance to capture data on the BSM issue (really it was 2 full days they had the car). Of course I had a loaner... They have some new diagnostic data logger that they used to capture data for Mazda USA.

They claim they couldn't replicate it, and to be fair, since I have gotten it back, it has triggered false positives on the driver side a few times quickly (not holding in an alert state). Before it would be holding illuminated for 15-45 seconds at a time. So maybe the replication issue was simply that they couldn't replicate the long held false positive (we also havent had any rain in a 7-10 days, so maybe its a moisture issue?)

But it is still happening somewhat so I am just waiting for the new modules to come in. I am going to ask they only replace the driver side first, as I don't want to mess with the side that has been working perfectly from day one.

 

[ccspeedsix]

Couple more drive cycles, and I am guessing that they went through a calibration procedure of sorts on the BSM, because the false positives are now just short blips. They are still occurring frequently enough, but they arent coming on and staying on for long periods of time. I am just waiting for the new BSM modules to come in and they will replace them in hopes of it fixing the problem.

The CEL I had was apparently (Secondary O2) sorted via a re-calibration (sounded like it was on the sensor itself), but there are some things I am finding odd now. Fuel economy has taken a noticeable hit (down 2-3 mpg avg on the current drive readout, on good days I was hitting 34/35 now I am hitting 32 pretty consistently). What is more odd is that it seems that iStop is behaving much more consistently and less aggressive, which definitely improves some of the odd / random NVH from shifts / slower speed dynamics.

I am unsure how much of things smoothing out with the low speed dynamics is break in vs. changing driving habits vs placebo since getting my car back. I am starting to suspect there may have been software changes applied, or whatever was going on with the secondary O2 actually has a measurable impact on engine control mechanics. Either way, those just living with the BSM problem should take their car in, I am curious to see if others will confirm some of the changes I am seeing (that didnt go in for CEL).

When I took the car in, I did complain about harshness in shifts / slow speed dynamics / aggressive iStop in addition to the CEL / BSM.

 

[MikeATL]

Couple more drive cycles, and I am guessing that they went through a calibration procedure of sorts on the BSM, because the false positives are now just short blips. They are still occurring frequently enough, but they arent coming on and staying on for long periods of time. I am just waiting for the new BSM modules to come in and they will replace them in hopes of it fixing the problem.

The CEL I had was apparently (Secondary O2) sorted via a re-calibration (sounded like it was on the sensor itself), but there are some things I am finding odd now. Fuel economy has taken a noticeable hit (down 2-3 mpg avg on the current drive readout, on good days I was hitting 34/35 now I am hitting 32 pretty consistently). What is more odd is that it seems that iStop is behaving much more consistently and less aggressive, which definitely improves some of the odd / random NVH from shifts / slower speed dynamics.

I am unsure how much of things smoothing out with the low speed dynamics is break in vs. changing driving habits vs placebo since getting my car back. I am starting to suspect there may have been software changes applied, or whatever was going on with the secondary O2 actually has a measurable impact on engine control mechanics. Either way, those just living with the BSM problem should take their car in, I am curious to see if others will confirm some of the changes I am seeing (that didnt go in for CEL).

When I took the car in, I did complain about harshness in shifts / slow speed dynamics / aggressive iStop in addition to the CEL / BSM.

Thank you for keeping us posted.

 

[Gus75]

https://www.youtube.com/watch?v=a1ydjD7cRx4
My son recorded the video on 5/2/2023

We were experiencing driver side blind spot monitoring system malfunction. It would randomly and falsely warn us of a car in our blind spot when there isn't. It sometimes just stays on for no reason when the car is in motion and even when stationary.

For some reason it hasn't happened as often the last few days. Was out driving for a couple of hours over the weekend trying to record it happening again, but the BSM was working fine for the entire 2 hours.

Maybe car was pushing water into bumper sensors and causing problems. My new cx5 had water inside both rear lights. I think the dealer used high pressure hose to wash car and pushed water into lens.

 

[ccspeedsix]

Maybe car was pushing water into bumper sensors and causing problems. My new cx5 had water inside both rear lights. I think the dealer used high pressure hose to wash car and pushed water into lens.

At this point I am seeing multiple people complaining of the exact same issue, only affecting the rear driver side BSM across multiple trim levels. Seeing folks on both forums and FB groups, so at this point its one of an assembly / sensor / software issue.

After I took mine in for this problem, they couldn't "replicate it", but whatever resets they had to do to the system did reduce the occurrences / cause them to only trigger as false positive blips vs. being held on for longer periods of time. After about 100 miles since getting the car back though, the system is starting to behave like it did prior to me bringing it in for diagnosis.

 

[MikeATL]

Did they give you an ETA on the BSM modules?

How is your Fuel economy now? I have not been able to get anything more than 23.5mpg (based on my own calculation when filling up). I have noticed that the car almost always report at least 2 mpg better than actual mpg. That's about 65% city, 35% highway of mostly gentle driving with Unleaded Plus gas.

 

[ccspeedsix]

I just pinged the dealer this AM, still waiting to here back on the modules.

Fuel economy has been slowly creeping up, each drive cycle is pretty close to what I was getting before. I think the "learning" cycle is just much slower then what I was expecting. iStop and BSM is behaving like it did prior, I dont think the software has changed. Transmission is just smoothing out a bit with drive cycles / miles.

I am probably more tilted towards highway (60/40) driving. The more stop and go you do its pretty dramatic the difference it makes. I am finding (with my average linked to trip A) only about ~ 1 mpg delta between hand calculation.

If I had to guess, the delta goes down with more highway driving (less accumulation of rounding errors?).

Also my miles to refuel seems to be calibrated to hit 0 miles with about 3 gallons of gas left (I am refueling near empty only 16.5 gallons, not 19.5). Probably a smart move anyways.

 

[ccspeedsix]

So BSM modules were supposed to have been replaced (dropped off on Monday), but apparently they are riveted in, and the rivets weren't included with the modules. The back order on the rivets is apparently 6 months, so I am not sure what they are going to do. I am confused as to why they are riveted in....

This is getting a little frustrating...

 

[MikeATL]

So BSM modules were supposed to have been replaced (dropped off on Monday), but apparently they are riveted in, and the rivets weren't included with the modules. The back order on the rivets is apparently 6 months, so I am not sure what they are going to do. I am confused as to why they are riveted in....

This is getting a little frustrating...

You may need to escalate this issue to Mazda. We have been in contact with mazdacustomerexperience@mazdausa.com ever since we filled out an detailed survey online for the Mazda CX-90 purchase and vehicle experience. They reached out to us via phone and email to see if there is anything they can help us with. I'm not sure if there is anything more they can do, but at least let them know how unhappy you are.

I was hoping you will have the BSM fixed, so I can get it fixed as well.

 

[ccspeedsix]

You may need to escalate this issue to Mazda. We have been in contact with mazdacustomerexperience@mazdausa.com ever since we filled out an detailed survey online for the Mazda CX-90 purchase and vehicle experience. They reached out to us via phone and email to see if there is anything they can help us with. I'm not sure if there is anything more they can do, but at least let them know how unhappy you are.

I was hoping you will have the BSM fixed, so I can get it fixed as well.

I think the dealership is working heavily with Mazda to get this sorted. Its just a matter of parts availability on a brand new vehicle.

Honestly I was more frustrated that it took 1.5 days of the dealership with my car for them to figure out they didn't have the rivets, then needed another 1.5 days to do a oil change and driver door wiring harness TSB.

Honestly, I don't know if the modules are going to fix it completely, as the PHEV loaner I had did have a brief blip or two false positive on the driver side with nothing there, but at least never did what my car does with it coming on and holding for long periods of time. I am guessing there is an edge case in the software that can be tripped by certain modules with either higher sensitivity, or worse noise cancelling / side-lobe cancelling. Cant rule out interference with other signals being encountered in the wild as well I am sure.

I have had the driver side parked car alert pop up once just by walking to the back when I was checking the luggage are. Its all apart of being an owner of a completely brand new platform, I am sure they will work hard to get things sorted, considering the investment Mazda must have put into the platform.

 

[MikeATL]

I think the dealership is working heavily with Mazda to get this sorted. Its just a matter of parts availability on a brand new vehicle.

Honestly I was more frustrated that it took 1.5 days of the dealership with my car for them to figure out they didn't have the rivets, then needed another 1.5 days to do a oil change and driver door wiring harness TSB.

Honestly, I don't know if the modules are going to fix it completely, as the PHEV loaner I had did have a brief blip or two false positive on the driver side with nothing there, but at least never did what my car does with it coming on and holding for long periods of time. I am guessing there is an edge case in the software that can be tripped by certain modules with either higher sensitivity, or worse noise cancelling / side-lobe cancelling. Cant rule out interference with other signals being encountered in the wild as well I am sure.

I have had the driver side parked car alert pop up once just by walking to the back when I was checking the luggage are. Its all apart of being an owner of a completely brand new platform, I am sure they will work hard to get things sorted, considering the investment Mazda must have put into the platform.

I think you are going to be correct about this problem will likely not be completely resolved by simply replacing the modules.

Last night we had another issue with our CX-90. My power liftgate would not close all the way after pressing the close button, even when there is no obstruction (this has happened a couple times before). A bit later the same night, it wouldn't close at all by pressing the button on the liftgate, using the remote or the hands-free foot kicking motion (The liftgate may have tried to move a bit upward, but no beep or anything else). Tried manually slowly closing the liftgate, but it will not fully latch close. Ended up having to manually lift up and close the liftgate again with more force to fully close it. Pressing the liftgate button on the remote again and still not working. But, it mysteriously started working normally maybe 10 minutes later. I tried "resetting the set fully-open position" by "press and hold the power liftgate close switch for 7 seconds" and I'm waiting to see if that will make any difference. The liftgate still seems to be working normally this morning. Very strange!

I'm afraid to take our car to the Mazda service department with our recent oil change experience: https://mazdas247.com/forum/t/be-careful-where-you-take-your-cx-90-for-service-and-check-for-damage.123879479/

 

[MikeATL]

BTW, could someone please check to see if you can hear a faint buzzing noise when the power liftgate is open? The sound seems to be coming from behind the rear bumper. I can hear it as long as the liftgate remain open. The sound would go away as soon as I press the close button. Ours has always made that sound since day one. I'm just not sure if it's normal.

 

[MikeATL]

So BSM modules were supposed to have been replaced (dropped off on Monday), but apparently they are riveted in, and the rivets weren't included with the modules. The back order on the rivets is apparently 6 months, so I am not sure what they are going to do. I am confused as to why they are riveted in....

This is getting a little frustrating...

Did you get your car back yet? Any updates on the BSM modules?

 

[ccspeedsix]

I did, but the modules couldnt be replaced as they are riveted in, and the rivets were not included.
Rivets are back-ordered, with my dealership system saying November could be is when new stock is coming in (they dont think this is correct, but just what their automated system is saying).

So I am waiting for them to source the rivets so they can replace the modules.

 

[MikeATL]

I did, but the modules couldnt be replaced as they are riveted in, and the rivets were not included.
Rivets are back-ordered, with my dealership system saying November could be is when new stock is coming in (they dont think this is correct, but just what their automated system is saying).

So I am waiting for them to source the rivets so they can replace the modules.

That really sucks! I took my CX90 in today for them to fix the damage they caused when they did the oil change. They replaced the cracked plastic undercover and they showed me that there were no further damage underneath. They couldn't duplicate the BSM issue today and I told them to make sure they document it and we'll wait and see if Mazda will put out a TSB for it.

This new error message just appeared on my CX90 earlier this afternoon after filling up my gas tank:

This time it showed "Driver Monitoring Camera Malfunction". So, the Driver Personalization System stopped working(camera didn't work, so it couldn't recognize the driver). Restarted the car a few times and it still wouldn't work. Left the car for a while and went back to try it and magically it started working again. This car is so glitchy.