Model Year 21/22 Front radar sensor scratched - will it need replacing?

May 15, 2025
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1
So I’ve just had a warning come up that my front assist is unavailable - sensor impaired alongside a proactive occupant protection system is restricted error. When looking at the front radar sensor I’ve noticed that there was a scratch along the top of it but it’s not something that has been an issue previously but now I have this constant error. I’d like to know if this warrants a replacement or if I can just fix it with a plastic scratch removal like meguiars plastx. If I do have to replace the sensor, will it need a complete replacement or just the plastic cover at the front as I understand these sensors are fairly expensive so I’m hoping cupra have some sense and the plastic can just be replaced. Oh and also, if I do need a replacement I’d like this to be a one time thing so ideally I’d like to protect it somehow, would some ppf be helpful or would that impact the effectiveness of the radar sensor
 
May 15, 2025
17
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The radar isn’t exposed, it’s clipped into the grill

do a diagnostic scan
Okay I’ll plug it in and have a look. Just out of curiosity, if it is that scratch that is causing the radar sensor to be impaired, do you know if I will be able to just replace the plastic cover or will the whole radar sensor need replacement
 
May 15, 2025
17
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Why would you replace the radar due to the grill being damaged?
I don’t want to, I just want to know if the plastic cover is scratched, if the radar sensor is attached physically to that plastic cover meaning I’d have to replace the whole radar sensor to get rid of the scratch or if I can simply take off the plastic cover, get a new one, attach it and calibrate the sensors. If I can avoid replacing the radar sensor I’d like to especially if it’s just from a stupid scratch on the plastic cover but having experience with previous seat models I know things can be over engineered to the point of fixes being needlessly expensive that’s why I’m airing on the side of caution and asking the forum.
 
May 15, 2025
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The fault codes and some images will help out immensely here.
I don’t have an obdscanner but have purchased one so will plug it in tomorrow to check the code. I have attached the image showing the scratch and if there’s any other advice anyone can give on how else to check, maybe there is a cable I can reach around to see if it’s loose? I’d very much appreciate any advice so i don’t have to visit the consistently useless dealer
IMG_4444.jpeg
 
May 15, 2025
17
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I would say that scratch will be having no impact on the function of the radar.

Does the warning come on every time you turn on the ignition?
Yes it has done since yesterday. I know these formentors are temperamental when it comes to the sensor faults but usually they disappear with a quick reset of the ignition or even a clean wipe of them. These faults however are always on.
I will say as well, I’m 90% certain that these scratches were on the sensor since I purchased the car which was 7 months ago now and this is the first time these faults have appeared. I’ll attach what the faults are on the infotainment as well
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May 15, 2025
17
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It isn’t a plastic cover. It’s the complete lower grill. I highly doubt it’s the scratch causing the issues

Do a diagnostic scan and go from there. Have you had a wheel alignment done recently? Are all of your tyre pressures correct? Has the front bumper been removed at all?
Yeah I’ll do a diagnostic tomorrow when the obd scanner comes. Regarding your other questions, no wheel alignment, no bumper removal either but I will reinflate the tyres later and see if that fixes the issue. Thanks for the suggestions
 
May 15, 2025
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If it’s upset it enough to want calibration then simply inflating them isn’t good enough (if they’re low/uneven pressures)

Depending on which tool you’ve bought, you should be able to run a dynamic calibration.
Ensure you have a full tank of fuel and the pressures are correct. No additional weight in the car
Do you think the dealer will cover a calibration under warranty as I’ve purchased the car from a cupra dealer so have been given a used warranty
 

Luner Lander

Active Member
Apr 8, 2024
23
3
It’s unlikely that the scratch (or scratches) are causing the issue as the frequency used by the radar module means the plastic cover is “transparent“ as far as the radar module is concerned. However, ingress of dirt or water into or on front of the cover would cause failure. It would be interesting to see what a scanner makes of it and the fault code(s) it reports.
 
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May 15, 2025
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So after plugging in the obdeleven and clearing all of the errors these are the only ones that persist and my dashboard is still showing the same front assist unavailable etc. Errors. Does anyone have an idea as to what these codes mean and what I can do to clear them up?
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Tell

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Well Formentors did use to give loads of error codes that may be better fixed these days. At launch it was a long as your elbow. If you clear them you get to know which is what but obviously if they dont all clear down you arent any the wiser. Dealers don't seem to clear them down these days so you get the car back after some work on it with errors created by what they did. That which they should have cleared down.

The old faithful I get on my Ateca is bus error. Not an issue. Doors open engine on or something creates that. Radar sensor blocked wet weather is another one. You just read down and say OK, I know that etc. Frequency and date.

No a scratch panel on the sensor won't affect it. It sees straight through that. Water can get inside them. I dont get it on the Ateca. Arona we do. Parked facing down a hill will cause it to get blocked in wet wezther. Weird one. Did it from day one. Once they dry out all is well. Obviously you haven't got any front assist protection or not within parameters when the warning light is on.
 
May 15, 2025
17
1
Well Formentors did use to give loads of error codes that may be better fixed these days. At launch it was a long as your elbow. If you clear them you get to know which is what but obviously if they dont all clear down you arent any the wiser. Dealers don't seem to clear them down these days so you get the car back after some work on it with errors created by what they did. That which they should have cleared down.

The old faithful I get on my Ateca is bus error. Not an issue. Doors open engine on or something creates that. Radar sensor blocked wet weather is another one. You just read down and say OK, I know that etc. Frequency and date.

No a scratch panel on the sensor won't affect it. It sees straight through that. Water can get inside them. I dont get it on the Ateca. Arona we do. Parked facing down a hill will cause it to get blocked in wet wezther. Weird one. Did it from day one. Once they dry out all is well. Obviously you haven't got any front assist protection or not within parameters when the warning light is on.
Thanks for the response. Unfortunately after a few days the error still persists. It can occasionally disappear for about 5 minutes on a drive but then reappear again and clearing the fault code again does nothing. What’s annoying is that once the error disappears for a little bit everything works perfectly fine adaptive cruise lane keep assist I’ve even approached cars fast to see if the emergency brake will warn me and it does but again after a bit the error just reappears.

Do you think that a recalibration of the sensor will clear the error permanently? I could also look at blowing some air into the gap hopefully that could clear any debris if there is any but I’m running out of ideas to be honest and I’m not really interested in spending hundreds if not thousands at sorting a new sensor
 

serdar_18fr

Active Member
May 29, 2021
674
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Thanks for the response. Unfortunately after a few days the error still persists. It can occasionally disappear for about 5 minutes on a drive but then reappear again and clearing the fault code again does nothing. What’s annoying is that once the error disappears for a little bit everything works perfectly fine adaptive cruise lane keep assist I’ve even approached cars fast to see if the emergency brake will warn me and it does but again after a bit the error just reappears.

Do you think that a recalibration of the sensor will clear the error permanently? I could also look at blowing some air into the gap hopefully that could clear any debris if there is any but I’m running out of ideas to be honest and I’m not really interested in spending hundreds if not thousands at sorting a new sensor


Calibration may fix things but the interesting thing is that the persistent faults are coming from the Driver Assistance control unit, meaning the camera on the windshield, not from the radar. A problem in some unit would definitely cause others also to throw faults but with no fault in the radar, not sure which unit is the suspect and may require calibration here.

Did you check the faults again, after you cleared them & drive 5 minutes & fault showed up on dash ? Still only those 5 persistent ones or also the newly thrown ones in radar too?
 
So after plugging in the obdeleven and clearing all of the errors these are the only ones that persist and my dashboard is still showing the same front assist unavailable etc. Errors. Does anyone have an idea as to what these codes mean and what I can do to clear them up? View attachment 50511
So there are no faults in any other modules? Nothing in the radar? These fault codes suggest otherwise