EM7455 GPS stops tracking


I have a large amount of units depending on the EM7455 with a external antenna for navigation, and for the last couple of months I have encountered some difficulites that I would appreciate some tips & tricks on.

Earlier this year I startet noticing that some of the units started loosing GPS FIX when there was no reason for it to loose GPS FIX. After some investagation a got FAILCODE = 0 when running AT!GPSSTATUS?.
At this time I was running with FW version 002.026_001.

I then flashed some of the devices up to FW version 002.038_000, I have since notied that some units still randomly loss GPS FIX, but the modem now reports FAILCODE = 12 when I query AT!GPSTATUS?.


As far as I can understand failcode 12 means GPS Timeout, but in all of the incindents I have enountered there is no reason for the GPS to loose fix. When analyzing the NMEA data It clearly shows that the modem can see 12-18 SV’s.

The weird thing is that in order to obtain a GPS fix again I have to do a reboot of the computer, or run AT!RESET. After said operation, the GPS instantly start tracking again.

I uploaded the NMEA-logs to SW GNSS Tool, and this is what it looks like when I run trough the data.
This node was static, so there was no enviormental changes in the given time.

All the modems are configured with GPS to start tracking at boot, like this: AT!GPSAUTOSTART=1,1,180,50,1
Other then that they are running on stock configuration.

Has anyone encountered anything similar?

Hi @Snoras ,
Welcome you to our community!
Could you please share with me some information as below:

  1. Can GPS be fixed on your EM7455 before? or is this your first time using it?
  2. Please share your procedure and AT commands log to start GPS position fixing.
  3. After start GPS position fix, on the devices cannot GPS position fix please share with me the output of commands below:
  4. Are the devices can be fixed and the devices can’t be fixed in the same location?


Hello @jerdung

Thank you for your response!
1 - Yes the EM7455 are able to obtain a GPS FIX, I have been using theses devices for a year. They usally work fine.

2 - I initiate a GPS tracking sessiong with AT!GPSAUTOSTART=1,1,180,50,1. So the tracking session starts on boot.

3 - yes, I’ve pasted below.


Current time: 2022 11 28 0 11:31:36

2022 11 28 0 11:29:43 Last Fix Status = FAIL, FAILCODE = 12
2022 11 28 0 11:29:43 Fix Session Status = ACTIVE


Not Available





4 - Yes, I have tested with mulitple devices. Initally everyone is tracking OK, but after some time one device might stop tracking, while the other devices still has a GPS FIX.
When the device stops tracking I have to reboot the computer or run AT!RESET to get it tracking again. This usally happens randomly, and on random units.

Hi @Snoras ,
Could you please share with me some information as below:

  1. What operating system are you using? (Windows or Linux)
  2. Have you installed latest driver on your host? If not, please install latest driver following the link below:
  • For Windows:


  • For Linux:


After installing the latest driver, please try again. Do the issue still happens in this case?


I’m running on WIN10.
Yes I’ve installed the latest driver and the latest firmware, the problem still occurs.


Does anyone know what this could be? I’ve read trough the docs and I can’t find a logical reason for the modem to behave like this…

Hi @Snoras ,
On failure modules, please make sure the antenna is still working.
If you have used the latest firmware and radio firmware on the same type of module and board, and the issue still happens on some of the modules, Please email tech support: support@sierrawireless.com for further support.


Hello again @jerdung123

I noticed this in the AT commands reference.


I dont think our devices is crashing, and our antennas are working fine. So it must be a problem regarding GPS Timeout. If that is the problem, how can I avoid the GPS timing out, and have the device tracking endlessly? My devices sometimes GPS track for many days in a row. Do you know if thats possible?

I also read this thread, but there is no clear answer there.
MC7354 gpsautostart question - IoT Modules / MC/EM Series - Sierra Wireless Forum

Thank you