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Workaround for notorious GPS problem on Forerunner 45s

4148870
over 3 years ago

As are many other people around here, I am also afflicted with GPS sometimes taking forever to find a fix on my Forerunner 45s.
Digging a bit into the problem, I found the reason, and how to work-around the problem, which I would like to share here.

Root cause (as I understand it)

In order to get a fix on the current location, GPS not only requires to get a signal from satellites, but also needs some sort of information on trajectories of them. So without any prior knowledge, a GPS device needs to "listen" to satellite signals for a while (ca. 15 to 30 minutes?) to guess their trajectories. Manufacturers like Garmin now assist the devices by providing information about the trajectories via internet. This, however, has to be kept up-to-date constantly. With Garmin, this assist is called CPE, and it should be updated whenever a watch is synced with the app on a phone that is connected to the internet.
When my watch has a current CPE file installed, I get a GPS fix in less than a minute. When the CPE file is expired, the GPS fix takes more than 20 minutes.
According to Garmin, the CPE file should be updated, every time the watch is synced with the app on my phone. Only, this simply does not happen.

How to check CPE status

If you have GPS problems, you can easily check if this is also the underlying cause in your case.
1. Long-press middle button on left side  --> menu opens
2. Tap middle button on left side once --> Info
3. Tap upper button on right side once --> Device-ID etc.
4. Tap middle button on left side once --> CPE status
This either states "CPE up-to-date" (or similar, I have German language), or "CPE expired".

How to work around

CPE is instantly updated when I sync the watch via USB-cable to Garmin-Express on my PC. So before I go out for a run, I check CPE status on the watch, and if it is expired, boot up my PC, start Garmin Express and plug in the USB-cable to watch and PC. Annoying, but it works...

My request to Garmin

As this is obviously not the intendes behavior of the watch, please fix it! 5 minutes of research on the internet tell me that the exact same problem afflicts many more products of your portfolio, and also that it is not a new problem. Honestly, if GPS is that unreliable, I could also simply buy a Chinese knock-off...

  • 0 over 2 years ago

    This is the solution I was looking for. My 45 has been almost un usable since v4.40FW update. Now its working as it should be. Thanks for posting

  • 0 over 1 year ago

    Thanks. This is the most useful tip i have come across to get the GPS working. It is a frustrating problem to deal with. Garmin should get this sorted.

  • 0 over 1 year ago in reply to 9343138

    Can you please expand on what you're personally experiencing? Is your watch taking a while to locate satellites until you sync with either your Connect app or Garmin Express? How often does this happen?

  • 0 over 1 year ago in reply to Garmin-Sierra

    . I have a FR45 since 2019. Over the last 2 years, the GPS is very irregular. Invariably it does not locate the satellites for nearly 30 mins. But over the day it does pick up. I have noticed that when i sync up with my PC it works more reliably. 

    The fix suggested in this thread seems to work like a charm. CPE "expired" is the reason for it to not connect with satellites it appears. But once i sync up and the status is "current" it appears to pick up connection a lot quicker. Hope this helps.

  • 0 over 1 year ago

    Thank you so much for this write up. I greatly appreciate your time and ingenuity to resolving this problem. My garmin 45 works great now. I could not have fixed it. Thank you so much.