anoop

As I was leaving an empty parking lot this evening in the rain the drivers side corner sensor lit up and chimed with "WARNING: Approaching obstacle" even though there was nothing. It did this many times even when I was turning right out of the parking lot, which made get back in the parking lot and drive around in circles trying to figure out why it's getting triggered. Eventually it stopped.

Has anyone had this happen to them? I would like to know in case this is a sign of a sensor going bad. I've driven a lot in the rain and never had it get triggered like this.

leomio85

Are you sure some piece of debris like a leaf didn't get partially stuck to one of the sensors due to the rain? I know on a steep decline out of my post office, the sensors will go off from the street itself when I forget to turn them off, so they're pretty sensitive.

anoop

That happens to me whenever I leave my driveway and it's not even that steep.

If a leaf got stuck to it, wouldn't it beep continuously till it was removed? This was on and off for about 3-5 minutes.

DriverOne

It's not because of the rain. I've had it happen to me in clear conditions, although just so people who don't own an RDX understand, it is not a common occurrence. I've had it happen I think twice in over two years when there was no clear cause. (The sensor can activate if you're going over a very steep dip, where the car thinks you're about to hit pavement. I have had this happen a few times, too, but I knew what was happening.)

leomio85

Ah, I misread your post, I thought it was going off continuously.

I would have said it's possible for heavy rain to mess with the sensor, but DriverOne is saying its happened to him in the clear, so maybe these sensors can just get glitchy. As long as it's not activating the crash mitigation system and slamming on the brakes for no reason, or becoming a recurring common issue, I'd say just chalk it up to a weird anomaly of having more and more electrical doo-dads in today's vehicles. If it becomes more common, I'd say that warrants a trip to the dealer for some warranty work.

ELIN

I posted this in the 2021 TLX Owner's thread but it sounds so similar to your issue:

ToniRDX19

Sometimes mine go berserk in the rain and any snow or ice accumulate on the sensor. It lit up the dash. Good thing it didn’t trigger a system emergency auto braking. This is annoying or worst could cause an accident. The proximity alert go nuts at heavy rain or going over deep puddle of water.

ELIN

If I'm being honest, it's probably the worst safety system in a car I've owned/leased.

I can definitely see this being an issue across the RDX, TLX, and the MDX when it comes out in a matter of days.

RDX-Rick

This thread was titled "Do Collision Sensors Malfunction In The Rain" and the OP was clearly speaking about Parking Sensors, when he mentioned "drivers side corner"

There seems to be some confusion between "Parking Sensors" and the "Collision Mitigation System"

Parking sensors are the 4 circular sensors mounted on both the front and rear bumpers. These sensors send out an ultrasonic (high frequency sound) signal, and then listen for it's echo to be returned from an object in front of it. These sensors can alert the driver as to how close he is to an object when parking. The faster the beeps, the closer he is to an object. These sensors will not cause the brakes to be applied, and will do nothing to prevent you from driving/backing into a nearby car. In fact they will usually not even alert the driver when another car is more than 5 feet away. The parking sensors , which are really just very small speakers, can act up if anything prevents them from vibrating. So perhaps a speck of dirt trapped in the ring around the sensor, or an extra heavy coat of wax can cause these sensors to give false alarms.

The "Collision Mitigation Braking" (CMB) and the "Adaptive Cruise Control" (ACC) both use a radar transmitter located behind the Acura logo in the front grill. Radar uses the same principal as the ultrasonic parking sensors, (ie. it measures the radar waves being reflected off objects in front) but instead of using high frequency sound waves, it uses high frequency radio waves. These radio waves are in a frequency band known as "microwaves".

The radar signal has a much greater range than sound waves, and therefore they are capable of detecting another vehicle at a much greater distance, which is needed in order to stop a vehicle going 70 MPH in time.

The problem with RADAR, is that microwave energy is absorbed by water. That is why your food gets hot in a Microwave oven, but plastic and glass plates do not. If you have ever had a Satellite TV system, you have probably noticed a loss of signal during heavy rains. You may have also noticed that your GPS will not work well during a rain, or if you are hiking under a heavy leaf canopy (water) that your GPS will fail to get a signal.

As a result the CMB and ACC systems will become disabled when the sensor (Acura logo) gets covered with slush.

The Blind Spot Monitor (BSM) also uses radar to detect vehicles in the blind spot. The same BSM radar unit also serves a second function as the Cross Traffic Alert (CTA). So both the BSM and CTA can be affected by water.

So remember when these systems act up, and either stop working, or give false alarms, it is not a defect with the RDX. It is simply a result of the laws of physics. The same thing happens will all cars that use radar for these functions. Subaru uses cameras instead of radar, but their system acts up when the windshield gets dirty. At least Acura went through the trouble of notifying the driver when these systems can no longer operate, so that he does not continue driving with the expectation that the system will save his butt.

dblwishbone

The driveway phenomenon is common; the parking sensors have a greater warning distance than I have experienced in other vehicles.

ELIN

My Benz probably uses a camera system as this never happens with any type of precip.

RDX-Rick

The original alert that you received, Radar Element Blocked, was indeed caused by your radar transceiver become blocked by water. You probably found that your Acura logo was covered with wet slush, which you wiped off. and resolved the original problem. As you said "no big deal". I specifically say that your radar was covered in wet slush because another interesting fact of microwaves is that they pass through solid ice quite easily.

Your second problem was with the ultrasonic parking sensors, which do not use any radar equipment at all. Therefore your concern that it was caused by a damaged radar unit is not a valid one.

You said that this second problem alerted you of an imminent impact. Once again the parking sensors have no control over the braking, and because of their short range, they could not alert you to an imminent impact unless you were driving less than maybe 3 MPH, and a collision at that speed should be damage free due to the shock absorbing bumpers.

You also say that as soon as you left the light, the problem stopped. The alert was probably caused by an obstruction or buildup of snow on the sensor, and the the obstruction didn't actually clear away when you started moving, but rather the warning system disables itself when vehicle speeds are above 5 MPH. That is why the problem seemed to re-occur at each stop sign, when the system reactivated itself. Actually each time you got the alerts it was being caused by the original obstruction.

I agree that it is frustrating that the radar unit became blocked with slush, but that is more due to the temperature and the type of flurries. Due to the location of the front radar unit, any ice or snow that contacts it, is likely to melt into wet slush due to the heat from the engine. In Ontario I normally experienced a blocked radar about twice each winter. This occurred with both my 2016 RDX and my 2020 RDX.

You can probably reduce the frequency of slush buildup on the sensor by using a hydrophobic coating such as a good quality wax, or a product like

NeverWet

NeverWet

. I have used NeverWet on a Satellite TV dish with great results, but a warning that it does dry with a cloudy appearance.

DJA123

On several occasions while reversing -- each time dry -- the rear proximity sensor has gone off as if there was an object VERY close behind me: red zone indicator and solid tone. Even though there was nothing on the camera, I had to get out and look because the system seemed sure there was something there. There was nothing. I think these occasional false alarms are just gremlins in this technology. I agree that the physics of reflected ultrasonic waves allow for occasional imperfect function. As you might imagine, a scan of other car forums will tell you that it's not just our cars that do this.

ELIN

What you're saying makes sense but it's quite annoying if I have to experience it again at every traffic light or stop sign. I understand there's no inherent danger but if I had a passenger, they may wonder how this could happen in a premium/luxury car. Perhaps Acura should have waited until the tech was fully mature before implementing, as Apple often does and why their products sometimes lags in features.

RDX-Rick

IF the problem should reoccur, and you don't have the opportunity to get out and clear the obstruction, then simply turn the system off with the button, until you get the time to address the cause.

The problem can occur with both front and rear sensors, but since the rear sensors are only active when the RDX is in reverse (and below 5 MPH), it will appear that the problem appears primarily in the front sensors.

As far as waiting until the tech was mature, I had these sensors first installed as a factory option on my 2008 Toyota, and I know that they were available for self install years prior to that.

I had the problem with my 2016 RDX, which would occur about once a week and last for several hours. I would turn the system off during that time. Whenever I had the time to look for the cause, the problem would not be occurring. Finally one day I took the time to clean the sensor thoroughly by removing the wax and using a toothpick to clean the circular grooves around the sensor. The problem never returned after that.

Of course I have no way of knowing if you have a defective sensor or not. If it reoccurs again, make a note if it is the same sensor or a different one. And then give it a good cleaning.

It's really not fair to criticize Acura because they can't change the laws of physics regarding the snow buildup blocking the front radar. With regards to the parking sensor, you may have a single defective sensor, or it may be due to a dirty sensor causing the problem. Once again it is not time to blame Acura without a little more proof.

Even if it is a defective sensor, Acura will replace it at no charge. With all the high tech components on these vehicles, having a single defective sensor should not reflect on the engineering and quality of Acura. I'm sure that many people have had false alarms with these parking sensors, but as far as I know, they have been single occurrences like yourself, and I don't recall anyone needing to get one replaced. So once again, another reason not to criticize Acura for poor quality vehicles.

In case you are wondering, yes, I have been happy with both of my RDX's. The only problem I had was when the the phone carriers dropped support for 2G, and I needed to get the AcuraLink receiver replaced in my 2016 RDX. That took several days due to lack of training for the techs. Once again, I can't blame Acura because cell phone tech changed. In fact they replaced the unit even though the new car warranty had already expired.

ELIN

I'm assuming it highly depends on the component. According to a lot of angry 1G TLX owners, there was a problem with the transmission that was at first denied by Acura, admitted fault later, but in the end did nothing.

I had a 2018 MDX AWD Tech which had the full complement of AcuraWatch features (I think). The implementation may have been different (there was no radar dish) but I never had this type of issue. Why would they change from that reliable setup to something that is less reliable? Here's a list of recent cars I've had without experiencing frequent nuisance alarms:

2013 E-Class 350 4MATIC
2015 Audi A6 3.0 Premium Plus
2016 GL450 4MATIC
2018 MDX AWD Tech

All have comparable safety systems and never an annoying audible alarm while sitting at a traffic light.

Before I forget: while turning off the system is a solution, it defeats the purpose of having a safety system in the first place. I've never needed to turn off safety!

RDX-Rick

Once again I feel that we need to recognize the difference between the "parking assist" feature and safety features ( i.e. Acurawatch safety technologies).

It's also not really clear if your main complaint is about your radar sensor being covered with snow, or your single front parking sensor beeping when you drive below 5 MPH. It's not also clear if the beeping sensor only occurred that single day you were driving in inclement weather or if the beeping is still occurring.

The Acurawatch package is a group of features which are designed to increase vehicle safety. This package includes:
1) Adaptive Cruise Control
2) Collision mitigation braking
3) Forward collision warning
4) Lane departure warning
5) Lane keeping assist
6) Road departure mitigation

The first 3 in this list make use of the front Radar transceiver (along with the camera in some cases). The last 3 in the list make use of the camera.

So far the only problem you had with a safety system was caused by a buildup of slush over the Radar sensor. At that time I believe you would have seen a message which advised you that ACC, CMB , and FCW were not available on your RDX. Also let's agree that this is not a malfunction of any piece of the RDX hardware,

As I said before, what happened to your parking sensor may have been a one time thing, or you may have a defective sensor, or simply a speck of sand trapped in the groove around the sensor.

You may not have had the radar problem in your other vehicles because you never drove in the same weather conditions, or the location, the slope, or the material covering the radar sensor was better at preventing slush buildup.

Once again the ultrasonic parking sensors are not considered a safety system. It is impossible for them to prevent a collision at 70 MPH when they can only detect an object 30" away. So you are not turning off a safety system when you disable the parking sensors.

I'm sure you realize that Acura gives you the ability to turn off each of the "real" safety systems as well. I don't think turning off a system defeats the purpose, but rather it gives drivers the choice to drive the way they prefer. If we were not able to turn off the systems, there would be a lot more complaints from owners saying they hate Acura for treating them like children and forcing them to use these systems.

I believe that the 2018 MDX had the same system, as my 2016 RDX did. If the radar system never became blocked on your MDX, then it was probably never driven in the same weather conditions.

ELIN

I can tell you now that all the cars I've mentioned (including the 2021 TLX) have all been driven in the same true 4-season NE US climates.

One November day in 2018, my state didn't do a proper job salting the road. A mixture of sleet/snow came down in the afternoon and the temps quickly dropped towards the early evening. My 15 minute commute back home took 3 hours. My poor wife came home after being on the road for 12 hours!

I had the MDX back then. If what I experienced in the current TLX happened to me that day, I probably would have gone crazy!

Just to be clear, I have no issue with the car telling me that some safety features aren't active because the radar is obstructed (this is good info). My main issue was the car telling me about an imminent impact coming to my right corner when I'm simply stopped at a traffic light at 0 mph (accompanied by annoying audible alarm)!

I will be keeping an eye on these phantom collision alarms.

JB in AZ

My son borrowed a previous car of ours that had the parking sensors. He and his wife said they would never buy a car with them because they go off all the time with beeps. When I asked them what were the conditions, they replied "while stopped at a red light" I said "What!? ... how could this happen?" It turns out, there were pedestrians walking by in the cross-walk in front of them that triggered the "parking sensors" LOL Once they understood, they later bought a car with them. These sensors have a VERY limited range. When I park our RDX in our garage they only "sound off' when I am only a few feet (2-3?) from the "hazard", the 55lb dog food bag on the garage floor, and they show the location (LF) on the screen..

ELIN

I can tell you that on that day, the alarm wasn't from pedestrians. Except for that one morning, the alarm has never gone off again and there have been plenty of pedestrians on crosswalks before and since. This is the way it should normally function.

Those pedestrians must have been really close to the bumper. Was your son in a major city?

kboo74656

My 2019 A-Spec was doing this with the parking sensors with nothing around to cause it. Took it to the dealer and they tested it and found a problem. They replaced the harness for the parking sensors and problem solved.

JB in AZ

Yes.

anoop

Definitely not up to par with the system in my 2015 328i.

anoop

Depends on if the impact is at bumper level or above. Anything above bumper level can cause extensive damage even at those speeds. I collided with an SLK roadster while backing up in a parking lot. Because of angle, the sensors didn't even beep until we hit. Their car was barely damaged--cracked tail lamp. Mine had $2500 worth of damage.

subin

I am on my 27th months with the 2019 SH-AWD Aspec and the heavy rain last week made this happened.
RDX was parked on the office lot without cover from around 10:00 ~ 19:00, when I left the lot, the parking sensor started beeping with notification of LF location.
I got off the car and checked, nothing there except rain left on the surface. So, I continued to drive and the warning would go off every few seconds for about 1/2 mile and then it just stopped doing this.
This is not my first time driving in the rain or left it parked under the rain and this was the first time I experienced this.

ELIN

Did the warning only come where you were stopped (ie. at a red light or STOP sign)?

subin

It came on when the car was moving, even at around 30 mph.

ELIN

That's very disturbing. As it results in annoyance rather than possible fatality, I'm guessing there will be no recall for this system.

DriverOne

Why would there be a recall for a problem that almost nobody is experiencing?

RDX-Rick

I understand that several owners have experienced this in the past, including myself, in my 2016 RDX. The important thing is that there is a low report rate of it happening, and for most owners it only happens 1-2 times in the lifetime of the car, and occurs mostly during inclement weather, which is not unexpected due to the physics used by the technology.

Also, as far as I understand, recalls are only related to safety items. For example if the problem causes the car to lose control , catch fire, or unable to stop. Despite my saying it several times, not having 1 of the 8 parking assist sensors working, during wet weather, should not cause a fatal crash.

If the problem occurred on a frequent basis, and was not a safety issue, then a TSB might be issued to help a mechanic fix the problem in the most efficient way, IF the problem should occur. In fact a TSB might also be issued for a safety recall to assist the mechanic in fixing the problem.

So I agree that it is unlikely a safety recall will be issued for this. If the problem reoccurs, then you may want to have an assistant get out and guide you into your parking space.

ELIN

It was a rhetorical statement (I know there will be no recall). The fact remains that I've had appreciable time with other luxury brands that never gave me that one time experience I had on the TLX. I've had the TLX for a bit over 3 months now but I haven't even hit 1000 miles yet due to the pandemic. I've logged thousands of miles on the other cars when I wasn't WFH, experienced many more days of inclement weather on the road, and never experienced the "bitching Betty" alert I experienced sitting at a stop light. I wouldn't be complaining if it was only a visual alert but there was sound too! You don't have to be an actuary or statistician to understand it doesn't put the current system in the TLX in a good light!

TimmyB83

I’ve routinely been keeping my parking sensors off now, as mine basically say something is in the red zone almost constantly. If you activate them while stopped, it’ll alert until about 5-10 mph and deactivate at your next stop. See videos attached.

anoop

The videos you posted are exactly the problem I am having.

Today it rained again. We don't get much rain around here. I checked the sensors and all was clean. But the sensors were still getting triggered every time I came to a halt.

I managed to take a video at a light.
https://www.dropbox.com/s/0c23zkde4u..._0734.MOV?dl=0

This continued throughout the drive today.

I will be mentioning this and the "Drive mode change unavailable" issue at the next service.

Wonder what they will do to fix these issues.

JB in AZ

There is a definite fix for the drive mode not available issue. They need to replace the instrument cluster. TSB for it. I'm not sure if it has been mentioned in this thread, as I didn't go back and read it all, but it is a known issue...was fixed on mine.

anoop

As I mentioned in the other thread, they fixed the "Drive mode change unavailable" issue by changing some connectors.

Unfortunately, for the parking sensor malfunction, they did nothing. They said that since there are no error codes and they can't duplicate the issue, they can't do anything. I plan to follow up with Acura since my car has only 8 months of warranty left. I'll send them links to the 2 videos I took showing the malfunction.