Limp mode with multiple error codes (2021 CX-9)

C

Costello

New here, but thought I'd throw this out there. My 2021 CX-9 has done this same thing 3 times. As I'm going up a slight hill, it suddenly goes into limp mode. 7 different warning codes flash on the screen - Driver Attention Alert is disabled, Engine malfunction, Dynamic Stability Control malfunction, front radar sensor malfunction, I-ACTIVESENSE system malfunction, Smart Brake Support (SBS) and Forward Obstruction Warning (FOW) systems are disabled. Once I pull over, turn the car off and restart, everything is fine and the messages go away. No more limp mode. It happened randomly about 3 weeks ago. The rep at the dealer said it can be caused by a battery that needs to replaced. This was true, so we replaced it. Now, today, it happened TWICE. The common denominator is that I'm going uphill. The weather has been average or warm, not excessive at any time. My MazaApp displays all of those error messages multiple times. Once I erase all the messages, the only message that still displays (and has displayed every day since the first time) is "In-vehicle communication network malfunction." Everything is working the way it's supposed to, but I still have that message showing up every day in my app (ONLY in the app). The dealer could not find any codes when I took it there the first time. They say the MyMazda app leaves a lot to be desired. But obviously there is still a problem. Going into limp mode on a hill is scary, trying to find a good place to pull off. It happened the first time on a freeway, second time out on a windy country road, and the last time on the freeway.
Any thoughts? Is this a front radar malfunction?
 
I wonder if it's the inclination (sensor, wiring, water sloshing somewhere?) or the load (stress on drivetrain).
 
I had the same thing happen here, but only ever one time. I made a thread about it after it happened.. No idea what caused it. It was extremely humid/foggy at the time, that's the only thing that stood out to me.

Even though I got all the errors on the screen, and in the MyMazda app, the dealer said there were no actual codes stored in the ECU.
 
Yes, our dealer said the same thing - no codes stored. But since it's becoming more frequent, I need to have this addressed. I'm hoping someone can shed some light on how it was corrected and what needed to be replaced.
 
I had the exact same thing on my 2018 CX-9. It would randomly happen. Same symptoms and warning light. You turn the car off and on again and it goes away. Even check engine goes away. Spoke to the dealer about it and said the only way was to bring it while in "limp mode".
Bought an OBD reader and read the following codes last time it happened P2229 and P061B.
Hasn't happened in 6 months. Fingers crossed but not too reassuring...
 
The dealer did hook up a reader and it had set no codes. They want to see the car when it's actively gone into limp mode with these errors on the display. They are about 40 minutes from where we live, and the 3 times this has happened, we've been a minimum of 45 minutes away, or longer. That's too far to drive in limp mode. Thankfully, it hasn't happened since Labor Day. After scavenging the internet for clues, we've decided to keep the front emblem very clean (the front radar is behind the emblem), and also the forward sensing piece up on the windshield (at the top behind the rear view mirror). We clean those areas off regularly to make sure there's no debris or bugs. It's just a theory, but we think something might have gotten stuck on one of those two places to cause the car to "freak out." Time will tell. I'll post when we've gone a few months with no incidents.
 
Costello said:
New here, but thought I'd throw this out there. My 2021 CX-9 has done this same thing 3 times. As I'm going up a slight hill, it suddenly goes into limp mode. 7 different warning codes flash on the screen - Driver Attention Alert is disabled, Engine malfunction, Dynamic Stability Control malfunction, front radar sensor malfunction, I-ACTIVESENSE system malfunction, Smart Brake Support (SBS) and Forward Obstruction Warning (FOW) systems are disabled. Once I pull over, turn the car off and restart, everything is fine and the messages go away. No more limp mode. It happened randomly about 3 weeks ago. The rep at the dealer said it can be caused by a battery that needs to replaced. This was true, so we replaced it. Now, today, it happened TWICE. The common denominator is that I'm going uphill. The weather has been average or warm, not excessive at any time. My MazaApp displays all of those error messages multiple times. Once I erase all the messages, the only message that still displays (and has displayed every day since the first time) is "In-vehicle communication network malfunction." Everything is working the way it's supposed to, but I still have that message showing up every day in my app (ONLY in the app). The dealer could not find any codes when I took it there the first time. They say the MyMazda app leaves a lot to be desired. But obviously there is still a problem. Going into limp mode on a hill is scary, trying to find a good place to pull off. It happened the first time on a freeway, second time out on a windy country road, and the last time on the freeway.
Any thoughts? Is this a front radar malfunction?
Click to expand...
So your mention of the "communication network malfunction" error reminded me of this video I saw awhile back:

Worth checking out, maybe something similar going on?
 
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