nRF9131 modem Init failure

RE: nRF9131 modem Init failure

Emmett Tagliere — Thu, 19 Mar 2026 09:48:22 GMT

Hi,

Yes lets continue in ticket #358011

Best regards

RE: nRF9131 modem Init failure

Øyvind — Thu, 19 Mar 2026 09:45:09 GMT

Hello,

Michal is currently out of office and I've been asked to follow-up this ticket. If OK with you, can we continue the discussion in ticket #358011?

Kind regards,
Øyvind

RE: nRF9131 modem Init failure

Emmett Tagliere — Fri, 06 Mar 2026 08:54:45 GMT

Hi, sorry for the ongoing messages, but wanted to updated:

I tried to switch between my nRF9131 and the nRF9131 that's on the EK I had around, and now everything works perfectly. so its not a short or hardware, I think there may be something wrong with the specific revision I have.

The chip that works (the one I took from the EK):

2346AH

The chips that don't work (at least the 5 I tested):

2402G7

Would love your help on how to make the chips I have to work like the EK version does, since we already bought a big quantity of them.

Thanks!

RE: nRF9131 modem Init failure

Emmett Tagliere — Fri, 06 Mar 2026 05:39:05 GMT

Also, I'm using softSIM, if that can also cause an issue.

Regards

RE: nRF9131 modem Init failure

Emmett Tagliere — Fri, 06 Mar 2026 05:37:39 GMT

Hi, I re-assembled the board a few times and tried again, still same issue, and I'm pretty sure there weren't shorts in all those times of re-assembly. (it was on fresh new boards each time).

Also, important to note, I dont get that error on the modem firmware that came on the chip, so if I just plug the board in and start the application, nrf_modem_lib_init(); returns successfully. Only after doing a modem firmware upgrade the -5 error happens.

So I wonder if there is something with the modem firmware / NCS / nrf9131 / nPM6000 versions that mismatch, which is causing the updated firmware to fail.

Looking forward to your insights.

Thanks

RE: nRF9131 modem Init failure

Emmett Tagliere — Thu, 05 Mar 2026 17:02:17 GMT

ok, I hope thats the case.

I'll try re-soldering again, while also sending the design files for review in a new private ticket.

Best regards and thanks

RE: nRF9131 modem Init failure

Michal — Thu, 05 Mar 2026 16:57:12 GMT

I have a feeling it may be possibly be a footprint or soldering issue with some of the internal modem connections being shorted, causing error in communicating with the modem.

Errno -5 is EIO, which would make sense, if the application core is unable to contact the modem because of that.

But that's just my intuition.

Best regards,

Michal

RE: nRF9131 modem Init failure

Emmett Tagliere — Thu, 05 Mar 2026 16:44:49 GMT

alright, will do.

I have tested on the EK yes, worked fine.

best regards

RE: nRF9131 modem Init failure

Michal — Thu, 05 Mar 2026 16:39:49 GMT

No, not yet.

It may be worth checking. I would recommend making another (private) ticket with your design (schematic in PDF and gerber files at the minimum) and then one of our hardware experts will check that.

By the way, have you tested this on an nRF9131 EK?

Best regards,

Michal

RE: nRF9131 modem Init failure

Emmett Tagliere — Thu, 05 Mar 2026 16:25:16 GMT

Hi,

I did not, not yet.

Did the analysis give any light as to the possible reason for the fault?

best regards

RE: nRF9131 modem Init failure

Michal — Thu, 05 Mar 2026 16:16:26 GMT

Actually, did you get a design review done by us?

Best regards,

Michal

RE: nRF9131 modem Init failure

Michal — Wed, 04 Mar 2026 17:13:18 GMT

Thank you for the information.

Best regards,

Michal

RE: nRF9131 modem Init failure

Emmett Tagliere — Tue, 03 Mar 2026 17:08:49 GMT

Hi,

Modem FW: mfw_nrf91x1_2.0.4.zip

NCS version: v3.1.0

Thanks

RE: nRF9131 modem Init failure

Michal — Tue, 03 Mar 2026 15:58:37 GMT

Hello,

To be able to analyse that, could you tell me your modem FW and NCS versions?

Best regards,

Michal