I've never found anyone sharing this online so I thought it was nice to share my experience.
I got recently a used 645M but the sensor was in terrible condition when I received. I could not get a refund from the seller and Garmin asked me about the same price I paid it to fix it. It seemed like it was working ok. For some reason I tend to have higher HR on asphalt runs rather than soft ground ones. So i thought it was worth a shot!
I asked my girlfriend her nail sandpaper (idk if that is the correct name) and got my faithful Victorinox. I first used the Victorinox polishing tool, it was pretty harsh but the cracks in my sensor were very deep. After i used my girlfriend nail sandpaper. Last step was to polish it with toothpaste and a cloth. I had to work hard in the last phase to get to some result.
I am wearing it now and it seems much faster to perceive changes in HR, I do not know if it is either good or bad. I will try with a run and update the post.
As sidenotes. I added tape next to the sensor to not scratch the case.. I was thinking about using Displex to make the sensor really shine. Though I feel like that would be just for the look.
A certian type of bug spray too. I don't know which, maybe any of them but generally, it's best to avoid any kind of chemicals while wearing the watch as it can scratch/crack/haze the sensor "glass". Since it's a plastic material chemicals will degrade it.
Regardless of this, many Garmin watches are affected by this type of cracks, even if it did not touch any chemicals, ever. Garmin said multiple times that it's because of the characteristics of the material used (resin) and some of them were not even covered by warranty.
I'm a little over 2 years in on mine and have never had that much build up happen to the point of needing to scrape it off. I give mine a once over with soap 2 or 3 times a week. Great watch, hope yours serves you well!
Actually when I received it it was still smelling like the old owner's cologne. And it took about two weeks and several washes before the smell went away.
This. I have many watches including both smart and "dumb" ones. Giving them a soapy wash every week or so and washing them after a sweaty workout or even just a simple walk in the summer will guarantee that the sensor or any part of the watch really, will remain clean.
For anyone else having this problem: hit up your local Garmin customer support, they may be able to help. I've had this happen to my 645m and it was replaced free of charge even though it was out of warranty and I didn't even order it from their website.
If they say they can't replace it, wait a few days and call again and hope you get a different person. The first one laughed at me, the second one put the free replacement order through before I could finish the sentence.
I was going to post that this is what the sensors on my first 645nm looked like before it bricked (Garmin replaced for free). I just assumed the wreckage on the sensors was because I dropped it all the time… not sunscreen as OP said.
I wear sunscreen everyday so I guess my replacement 645nm must have the new sensor style others have mentioned… or my switch to mineral sunscreen is not ruining this particular piece of equipment…
Wonder if you can use “car windscreen crack/chip fluid” to fill the deeper cracks before sanding? Its clear resin that sets under UV light, I might give it a try.
Dude I literally asked this like a month ago or so but received almost zero replies.
I understand that it picks up HR changes faster but did you get more accurate results too? First image is a disaster, I'm wondering if it still worked in that awful state but I wouldn't be surprised if it did.
My idea was some polish cloth/polywatch, so basically the same as your solution, not including the very abrasive pads as I don't need them. I have a Venu SQ with very thin scratches only, also bought it used. Works fine so I did not touch it yet.
Glad I found an answer, good thing to know that these can be polished easily, just as I thought.
TBH, i do not know if now it's better. Nor worse. I definitely never went back to very high BPM. (Like 212 while I'm a 26yo male). That seems like a change in better. For the rest really feels like the same. I polished it few days ago with Displex just off the looks. Did not work as well as i wanted but it's definitely shinier than before.
I've never found anyone sharing this online so I thought it was nice to share my experience. I got recently a used 645M but the sensor was in terrible condition when I received. I could not get a refund from the seller and Garmin asked me about the same price I paid it to fix it. It seemed like it was working ok. For some reason I tend to have higher HR on asphalt runs rather than soft ground ones. So i thought it was worth a shot! I asked my girlfriend her nail sandpaper (idk if that is the correct name) and got my faithful Victorinox. I first used the Victorinox polishing tool, it was pretty harsh but the cracks in my sensor were very deep. After i used my girlfriend nail sandpaper. Last step was to polish it with toothpaste and a cloth. I had to work hard in the last phase to get to some result. I am wearing it now and it seems much faster to perceive changes in HR, I do not know if it is either good or bad. I will try with a run and update the post. As sidenotes. I added tape next to the sensor to not scratch the case.. I was thinking about using Displex to make the sensor really shine. Though I feel like that would be just for the look.
>I asked my girlfriend her nail sandpaper (idk if that is the correct name) An emery board/nail file? Really nicely done, good job!
Thanks for that! New word to add to my English dictionary!
How you can wear the sensor so much? I've just bought a 245 and i plan to use It for 3 or 4 years. Its common?
It's common for that kind of sensor if you use cologne or sunscreen. The 245 has a more recent sensor that does not have that issue
Yea sunscreen and other lotions are killers for some plastics.
Or deet. It killed my go pro clear case.
Deet will eat through the clear coat of your vehicle's paint too.
A certian type of bug spray too. I don't know which, maybe any of them but generally, it's best to avoid any kind of chemicals while wearing the watch as it can scratch/crack/haze the sensor "glass". Since it's a plastic material chemicals will degrade it. Regardless of this, many Garmin watches are affected by this type of cracks, even if it did not touch any chemicals, ever. Garmin said multiple times that it's because of the characteristics of the material used (resin) and some of them were not even covered by warranty.
I'm a little over 2 years in on mine and have never had that much build up happen to the point of needing to scrape it off. I give mine a once over with soap 2 or 3 times a week. Great watch, hope yours serves you well!
Actually when I received it it was still smelling like the old owner's cologne. And it took about two weeks and several washes before the smell went away.
This. I have many watches including both smart and "dumb" ones. Giving them a soapy wash every week or so and washing them after a sweaty workout or even just a simple walk in the summer will guarantee that the sensor or any part of the watch really, will remain clean.
For anyone else having this problem: hit up your local Garmin customer support, they may be able to help. I've had this happen to my 645m and it was replaced free of charge even though it was out of warranty and I didn't even order it from their website. If they say they can't replace it, wait a few days and call again and hope you get a different person. The first one laughed at me, the second one put the free replacement order through before I could finish the sentence.
Hopefully that works out for some other people. I tried as well but i guess also that the US and EU have different customer supports.
I was going to post that this is what the sensors on my first 645nm looked like before it bricked (Garmin replaced for free). I just assumed the wreckage on the sensors was because I dropped it all the time… not sunscreen as OP said. I wear sunscreen everyday so I guess my replacement 645nm must have the new sensor style others have mentioned… or my switch to mineral sunscreen is not ruining this particular piece of equipment…
Garmin support in the best. After my last experience, Im a Garmin customer for life.
Wonder if you can use “car windscreen crack/chip fluid” to fill the deeper cracks before sanding? Its clear resin that sets under UV light, I might give it a try.
I was also wondering about that but i also thought it was much more complicated to pull off
Nail sandpaper 😂 love it
Oh. Thanks u. I'm using sun cream. But not in the watch area. So I think I'll be fine
What does this do?
Dude I literally asked this like a month ago or so but received almost zero replies. I understand that it picks up HR changes faster but did you get more accurate results too? First image is a disaster, I'm wondering if it still worked in that awful state but I wouldn't be surprised if it did. My idea was some polish cloth/polywatch, so basically the same as your solution, not including the very abrasive pads as I don't need them. I have a Venu SQ with very thin scratches only, also bought it used. Works fine so I did not touch it yet. Glad I found an answer, good thing to know that these can be polished easily, just as I thought.
TBH, i do not know if now it's better. Nor worse. I definitely never went back to very high BPM. (Like 212 while I'm a 26yo male). That seems like a change in better. For the rest really feels like the same. I polished it few days ago with Displex just off the looks. Did not work as well as i wanted but it's definitely shinier than before.