I have a 2018 CX 5 with 134,000 miles on it. 2 days ago when I was driving in town all of a sudden, a warning sounded and the parking brake symbol came on, the smart city brake system malfunction, smart brake system malfunction and front radar sensor malfunction lights came on. If I turn off the cruise control the radar sensor warning goes away. The car drives fine and I have brakes. What could be wrong? Amyone else have these issues?

 

You need to get an ABS Control module readout as well check for any and all DTC both pending and permanent.

 

Welcome to the forum

 

Can you explain that in more detail please? How do I get that read out? And what is all DTC mean?

 

Please don't take this wrong but if you are asking then you should find help probably a service shop that you have trust in.

 

I also have a 2018 CX-5. I've owned it for less than 1 yr. In my case the warning started recently about 30 minutes after driving through a car wash. I get two alternating messages; Front Radar Sensor System Malfunction & Smart Brake System Malfunction. Mine do not reset after turning the car off nor enabling, disabling cruise control. After seeing a few threads that mentioned cleaning the large Mazda emblem on the front grill (presumably housing the front sensor) I cleaned mine off but that was no help. It seems odd that these began shortly after the car wash. I wonder if maybe the sensor was loose and was jostled out of position or something. Is it rare that one of these sensors actually goes bad and needs to be replaced?

 

You should still have a WARRATY covering your Mazda. I suggest that you go to a MAZDA dealership. *No it is not a common issue. The fact that it happened after a car wash suggests the sensor(s) were contaminated or connectors? Also, a scan of your complete system and or flash with the most current ECU and other computer-controlled components updated?
This is all about your BRAKE SYSTEM and should be looked at ASAP.

Welcome to the forum.

* We frequently wash engine compartments and complete exterior of some customers vehicles including those with Radar Sensor System Malfunction & Smart Brake Systems without any problems. The engine components under the hood as well exterior mounted including the ECUs TCM etc., are well sealed and protected from wet conditions in most vehicles like Mazda's from at least 2013 to present.

 

Bad battery and dirty sensors can also cause this issue.
If you've checked that out than you'll need a diagnostic test as Cali said.

 

I just replaced the coil packs and plugs on my 2018 Mazda CX-5 using a kit from #partszen via Amazon. Car had 77,400 miles on it. Five days later both the "FRONT RADAR SENSOR SYSTEM MALFUNCTION" and "FORWARD SMART CITY BRAKE SUPPORT MALFUNCTION" warnings popped up on the dash at the same time the car felt like it was trying to brake, and then it went into Limp-Home mode. Diagnostic scans showed cylinder misfires on 3 of the four cylinders with the cause being an ION Sensor Circuit failure. I had the old (OEM) coil packs and plugs re-installed. Cleared all codes and runs fine. So the issue with my car was coil packs that were not compatible with, or not manufactured properly, for Mazda CX-5 applications. The Mazda dealer says they have seen this issue with non-OEM electrical components (made in China) numerous times.

 

If your Mazda model was produced during a certain date range and sometimes a specific VIN number range it might benefit from this Mazda Service Notice. My 2019 Mazda had Front Radar Sensor System Malfunction and Smart Brake System Malfunction warnings and this problem was apparently fixed when technician did something relating to this specific notice.

MC-10182100-0001.pdf