I am struggling with the same issue too.
Phantom 4 Special Edition Black.
Calibrated everything - no change.
I continue flying anyhow, and as of yet, no hard landings. I choose to land to ground manually.
In for answers...

Geebax Posted at 2018-4-4 22:17
Given trhat the P4P does not have a downward IR sensor, I would Not be concerned about it. Just more sloppy DJI code.

Hello flying friends:  I am here to say that I got the same warning with my Mavic Pro.   From what I have been reading the cause of the warning is still unknown.  They also cause me to be on the lookout for furthur happenings.  I just wanted all of you to be aware that the P4P and P3P drones are not alone when it come to this problem.  I hope the mystery gets solved

I've also got this problem on my brand new DJI Mavic Pro. When i take off I get the downfard infrared failure, or it keeps on ascending without me moving the joystick. Then i cant go down with the throttle. When i do full throttle down for some seconds the drone goes into landing mode and starts landing by it self and i cant cancel it. The VPS says its around 0.2 meters away from the ground but in fact its above my maximum flight altitude (around 100 meters) and it keps on getting higher. When it goes to landing mode i descends slowly until it reaches the ground.
What have i tried:
Updating all firmwares, updates. Refresh the firmware.
Calibrated IMU, Compass, VPS, Controller
Cleaning the Downward VPS sensors

Last night i get this error too on my DJI Spark...
Is there any solution from JDI?

fans36d15fdc Posted at 2018-5-12 12:01
Last night i get this error too on my DJI Spark...
Is there any solution from JDI?

I got this message from an admin. If you look at the thread, I sent data that they reviewed, and then responded with the message that the Ultrasonic Sensor Error was not real.

Link

Jeff
Edit: BTW, I flew three batteries today each down to 35%. I got the sensor error one time on the third flight. I ignored it and kept flying. The rear LEDs were on solid red when I landed. After a reboot it was fine.

Jeff Millard Posted at 2018-5-12 12:43
I got this message from an admin. If you look at the thread, I sent data that they reviewed, and then responded with the message that the Ultrasonic Sensor Error was not real.

Link

Well the DJI techos may know what they are saying but if the message was not real, why do both rear lights turn red. That, in itself, indicates an error somewhere. It may be that the message shown is not the actual problem but is a message to indicate there is a problem.

Jenee 2 Posted at 2018-5-12 22:46
Well the DJI techos may know what they are saying but if the message was not real, why do both rear lights turn red. That, in itself, indicates an error somewhere. It may be that the message shown is not the actual problem but is a message to indicate there is a problem.

I’m not going to second guess them. Their response to me was that the error is misinformation. As long as it’s under warranty and they indicate they’re aware of the problem and are working on it, I’m going to ignore the issue. At some point there will be an update. If they fix it, hooray. If not, I’ll open a repair ticket and send it back to them.

As a response to your post, I will spend a little time trying to figure out if there actually is a failure of the sensors. As soon as I can find the time. This is a very busy time of year for me.

Jeff

Hi message from the Netherlands: I got this message couple of days ago on my Phantom 4 Pro and i think after the last update: Ultrasonic sensor error! Land Immediately. Is the Ultrasonic sensor the same as Downward infrared Sensor?
Do i really have to land or can i ignore this message?
Edwin

Vayreda Posted at 2018-5-13 15:00
Hi message from the Netherlands: I got this message couple of days ago on my Phantom 4 Pro and i think after the last update: Ultrasonic sensor error! Land Immediately. Is the Ultrasonic sensor the same as Downward infrared Sensor?
Do i really have to land or can i ignore this message?
Edwin

Most users who have the Downward Infrared Sensor failure found the Phantom landed heavily possibly because it could not sense the distance to the ground. I am not sure about the Ultrasonic Sensor error.
These error messages mostly appeared after the last firmware update but I suspect that is because there has been some code included to pick up an error that was not previously picked up.
I would not ignore the error and I would land as soon as is practicable. If you are not able to land straight away then I would be extra careful.

Thanks Jenee2

I have download the latest update and suddenly the problem disappeared...i thought it is just a false alarm maybe...

I have a Mavic Pro giving the same error. First flight was 01/01/18 and started getting the error sometime back in March. Firmware refresh and all the calibrations doesn't help. Comes on about 3 minutes into each flight and the rear LED light turns red for the remainder of the flight. It doesn't seem to interfere with the flight you just have to remember to manually land it.

When I have received this error, the P$ has not been stable near the ground and either went up on it's own or started down on it's own very fast.  There is a problem when I get this error

Still have this error every single flight...
Can't believe there hasn't been a fix! It started with the most recent firmware. Auto take off is wonky too. Just starts ascending till i manually take control of the flight...
Still in for answers...

I am in the same situation: downwards sensor error, the status leds are solid red. I did upload flight log to airdata.com and behold: the flight log is riddled with "Warning        getWave Error (repeated 50 times)",

Hi All,
Thank you so much for your patience! For the Downward infrared sensor failure, we recommend updating the APP to the latest version to see whether the issue remains. Currently, there is a P4P beta firmware (V01.06.0100) fixing the Ultrasonic Sensor Error. If the reminder appears in the open field when the drone is in the air, it might be the misinformation. You may leave or PM us your DJI Account here, we'll collect regularly and forward to the right team to add you in the beta test. Any feedback will be appreciated.

Hello pilots
I have the same problem with my P4P. I had suspended flights for almost 1 month, today October 8, vole my phantom in Manta - Ecuador and the error message occurred. Just days after my care refresh is over.

Has anyone verified if the problem is only with the phantom 4 pro?

Hi today I had a serious problem with this issue in my dji spark. Infrared downward sensor failure land as soon as possible I was at 300 m of height and it marked 0 and suddenly started to take off, fortunately I could react quickly and after a couple of seconds the real height appeared again. How could I fix this serious problem, remember that your products are expensive and even more in South America please help me how could avoid these

Hi today I had a serious problem with this issue in my dji spark. Infrared downward sensor failure land as soon as possible I was at 300 m of height and it marked 0 and suddenly started to take off, fortunately I could react quickly and after a couple of seconds the real height appeared again. How could I fix this serious problem, remember that your products are expensive and even more in South America please help me how could avoid these

Hi, today I had a serious problem with this issue in my dji spark. Infrared downward sensor failure land as soon as possible I was at 300 m of height and it marked 0 and suddenly started to take off, fortunately I could react quickly and after a couple of seconds the real height appeared again. How could I fix this serious problem, remember that your products are expensive and even more in South America please help me how could avoid these

I get that all the time, not quite sure, but I believe it has to do with the sensors not recognizing the texture in the terrain directly under it. With me it happens when over grass, or water. I do hope it’s a software issue though. At first I would land but now unless I see wierd behavior, which I never have, i just keep flying.

DJI Susan Posted at 2018-7-5 22:38
Hi All,
Thank you so much for your patience! For the Downward infrared sensor failure, we recommend updating the APP to the latest version to see whether the issue remains. Currently, there is a P4P beta firmware (V01.06.0100) fixing the Ultrasonic Sensor Error. If the reminder appears in the open field when the drone is in the air, it might be the misinformation. You may leave or PM us your DJI Account here, we'll collect regularly and forward to the right team to add you in the beta test. Any feedback will be appreciated.

Hello everyone!

Did you find any solution to this problem? I've got this error and red lights after my 4 flights my brand new Phantom 4 Pro. In the DJI GO4 logs there's no trace of it... I have only "Mobile device CPU fully loaded. Related performance will be affected." - but I see this information for the first time... I didn't get this during fly...

I'm the new user and really afraid about it!

PABLO04 Posted at 3-18 23:41
Hello everyone!

Did you find any solution to this problem? I've got this error and red lights after my 4 flights my brand new Phantom 4 Pro. In the DJI GO4 logs there's no trace of it... I have only "Mobile device CPU fully loaded. Related performance will be affected." - but I see this information for the first time... I didn't get this during fly...

Sorry for the late response. Could you provide us with your DJI Account? I'll help you get the beta to see whether it helps. For the CPU reminder, it may pop up when the CPU of the mobile device is fully loaded. It is recommended to prevent the mobile device from direct sunlight with a sunshade or monitor hood.

My Mavic pro also started reporting a bug. Downward sensor error.Aircraft unstable at low altitude. Please fly with caution. When I take off so everything is fine.
I can fly in about 6 meters height without any problems, everything works as it should.
As I start to rise, a message appears .Downward sensor error.
Mavic stops responding to the stalk and starts to rise alone.
The red light turns on.
RTH begins to drop but the sensors do not respond to landing and land hard.
When you start again, everything repeats, green all right but as it rises above 6 m and red light.
All updates and calibrations are performed.
Do you know if these problems have already been solved?
I haven't found an answer yet.
Mavic is 2 years old.

DJI Susan Posted at 2018-7-5 22:38
Hi All,
Thank you so much for your patience! For the Downward infrared sensor failure, we recommend updating the APP to the latest version to see whether the issue remains. Currently, there is a P4P beta firmware (V01.06.0100) fixing the Ultrasonic Sensor Error. If the reminder appears in the open field when the drone is in the air, it might be the misinformation. You may leave or PM us your DJI Account here, we'll collect regularly and forward to the right team to add you in the beta test. Any feedback will be appreciated.

Hi susan,
a problem like this was happened in my mavic pro. I have never had an accident and have used it for a year. the last flight brought up the downward sensor error notification and the mavic rear lights flashed solid red. I did not dare automatic landing, I caught it. This happened after I upgraded to DJI Go 4 version 4.3.24

djiuser_xecGa9WyiSdb Posted at 9-12 18:33
Hi susan,
a problem like this was happened in my mavic pro. I have never had an accident and have used it for a year. the last flight brought up the downward sensor error notification and the mavic rear lights flashed solid red. I did not dare automatic landing, I caught it. This happened after I upgraded to DJI Go 4 version 4.3.24

Just to verify, does the issue appear in every flight and every place? If yes, may I have the issue video and the corresponding flight log in the aircraft for further analysis? Thanks so much!

DJI Susan Posted at 9-13 23:10
Just to verify, does the issue appear in every flight and every place? If yes, may I have the issue video and the corresponding flight log in the aircraft for further analysis? Thanks so much!

Yes susan, in every flight and every places...after this notif pop up, The rear lights are red, and I dare for auto landing...

Today i try to downgrade DJI Go 4 from 4.3.24 to 4.3.20 android...but the same issue still appears

djiuser_xecGa9WyiSdb Posted at 9-23 04:31
Yes susan, in every flight and every places...after this notif pop up, The rear lights are red, and I dare for auto landing...

Today i try to downgrade DJI Go 4 from 4.3.24 to 4.3.20 android...but the same issue still appears[Image]

Sorry susan, this is my version page...thanks

djiuser_xecGa9WyiSdb Posted at 9-23 06:54
Sorry susan, this is my version page...thanks

Thanks for getting back to us. Please kindly sync the flight records and advise the issue date and time, and refer to the below to export the corresponding flight log in the aircraft, we'll forward to our engineers for analysis.  

a. Download and install DJI assistant 2. Download Link:http://www.dji.com/mavic/info#downloads
b.Connect aircraft and PC, and power on the aircraft
c. Operate DJI assistant 2, find flight record and save

DJI Susan Posted at 9-24 18:45
Thanks for getting back to us. Please kindly sync the flight records and advise the issue date and time, and refer to the below to export the corresponding flight log in the aircraft, we'll forward to our engineers for analysis.  

a. Download and install DJI assistant 2. Download Link:http://www.dji.com/mavic/info#downloads

Hi susan,.

Yesterday i was update DJI Go 4 vers 4.3.25 for android...the last version of DJI Go 4 for android and the caption about update is "bug fix". After that, my trouble was clear...thanks

Satrya- Mavic Pro Posted at 10-6 05:22
Hi susan,.

Yesterday i was update DJI Go 4 vers 4.3.25 for android...the last version of DJI Go 4 for android and the caption about update is "bug fix". After that, my trouble was clear...thanks

Nice to hear the trouble was clear. Wish you have a good time!