2023 Civic Touring – Intermittent Brake System / Low Speed Braking / Parking Sensor Warnings

[skhan]

Hi everyone,

I'm looking for some input from anyone who has seen this before, especially Honda technicians.

Vehicle:

• 2023 Honda Civic Touring
• Approximately 30,000 miles
• Vehicle otherwise drives perfectly normally

Issue:

Over the last ~3 years, I've had approximately 5 occurrences where multiple warnings appear simultaneously. Most occurrences happened when starting the vehicle. The most recent occurrence happened while the vehicle was idling in Park after it had already been running for several minutes.

Warnings shown (attached images too):

• Brake System Problem ("Brake performance may be reduced")
• Low Speed Braking Control Problem
• Parking Sensor Problem

The warnings always clear after restarting the vehicle. It's otherwise been extremely reliable -- no issues at all. Interestingly though, the most recent occurrence happened while idling, not during startup.

Dealer findings:

• Battery tested healthy.
• Charging system tested healthy.
• No ABS-related DTCs reported.
• No VSA-related DTCs reported.
• No brake-system-related DTCs reported.
• Dealer only found parking sensor DTCs affecting all parking sensors: B2625-96, B2627-96, B2628-96, B2629-96, B2630-96, and B2631-96. The codes were inactive at the time they were pulled.

One thing that has me puzzled is that the dash reports a brake system problem, but the dealer is apparently not finding any brake-system, ABS, or VSA faults.

Aftermarket electronics:

• I have a hardwired radar detector and dashcams using fuse taps in the interior fuse box.
• The installation uses its own fused circuits and chassis ground.
• These were installed roughly a year before the first occurrence.
• The radar detector and dashcams have never rebooted, lost power, or shown any abnormal behavior.
• A Honda technician noted the aftermarket wiring as a possible factor, but there is currently no evidence linking it to the fault.

Questions:

• Has anyone seen this warning combination before where only parking sensor-related DTCs were present?
• If so, what ended up being the root cause?
• Did it end up being a sensor, parking sensor control module, communication issue, wiring issue, power/ground issue, etc.?
• Is there any known relationship between parking sensor faults and the brake system warning shown on the dash?
• Would this concern you from a safety standpoint, or does it sound more like an intermittent nuisance fault?

My lease ends in about two months, so I'm trying to determine whether this is simply an intermittent annoyance or something that would make you hesitant to own the vehicle long-term.

Also, this is my first time on the forum -- apologies if I posted in the wrong section.

Thanks.

 

[Aden Rich]

Those DTCs explain the whole cascade. The Low Speed Braking Control relies entirely on the parking sensors to see obstacles. If that sensor module hits a tiny voltage drop or glitches for a split second, the low speed braking system goes blind and automatically triggers that scary "Brake System Problem" master warning on the dash.

That’s exactly why the dealer didn't find any ABS or VSA codes—your actual mechanical brakes are 100% fine. Because all the sensors threw a code at the exact same time, you don't have bad sensors; the module just had a brief communication hiccup, which could easily be a minor voltage ripple from your dashcam or radar taps.With it only happening 5 times over 3 years, it's just a ghost in the machine. I wouldn't let it scare you off buying out the lease if you love the car, but if you're already on the fence, it's a perfect excuse to walk away in two months.

 

[skhan]

Those DTCs explain the whole cascade. The Low Speed Braking Control relies entirely on the parking sensors to see obstacles. If that sensor module hits a tiny voltage drop or glitches for a split second, the low speed braking system goes blind and automatically triggers that scary "Brake System Problem" master warning on the dash.

That’s exactly why the dealer didn't find any ABS or VSA codes—your actual mechanical brakes are 100% fine. Because all the sensors threw a code at the exact same time, you don't have bad sensors; the module just had a brief communication hiccup, which could easily be a minor voltage ripple from your dashcam or radar taps.With it only happening 5 times over 3 years, it's just a ghost in the machine. I wouldn't let it scare you off buying out the lease if you love the car, but if you're already on the fence, it's a perfect excuse to walk away in two months.

thanks for the response! would you think there is any reason to remove the hard tap? voltage ripple sounds like something mostly harmless, just curious if something worse could develop with time.

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