I've had an OVMS module in my Ioniq 5 since I got it new in summer 2023. It worked fine until December 2025 (though I only noticed recently), when it stopped reporting.
Having looked at the issue, the device's own AP is still available but now rejects any passwords. The cellular connection is still active, but no data transfer. Most weirdly, if you power cycle the thing, it will run normally for several hours, transferring data over wifi (connected to the house AP) or cellular, and allowing for connections to its own AP with the correct password, before reverting into this state.
Tried an older firmware I know was good and the latest, both exhibited the same behaviour.
It does seem like the ESP32 has gone peculiar, but i wanted to ask if anyone else has experienced this? Is there a fix, or is it going to be easier for me to just open it and swap in a new ESP32?
Over a similar time frame I've had increased reliability issues trying to wake the OVMS for commands, and previously reliable scripting now not working - there has been a lot of edge firmware updates over the period (need 3.3.005 for features in scripting I believe) and some of those really upset the reliability of the OVMS in my experience.
That's the funnything - as I'd been on a beta build for the Ioniq 5 support when I first got the unit, at some point autoupdates failed and I didn't notice, so it was actually on the one build for the majority of the past few years. The problem started to happen despite no change in software, hence my suspicion that it's a hardware fault (obviously I did try updating in case it was a rare bug, but behaviour is unchanged with a new mainline firmware).
I did take a look inside and the throughhole solder joints look a bit weird - somewhat corroded, like maybe too much flux was left on them for a long time. However, none of those pins would really explain the ESP32 misbehaving itself (like it still having a hotspot, just rejecting its known password).
I didn't actually swap ESP32s yet though I bought a four pack of the same sort so I am ready to. It's just a pain desoldering ESP32 modules so I need to get into the mood ;)
I decided before messing around with the ESP32 to actually check out the corrosion - I cleaned it off with IPA and it was actually wicking through the solder joints to the connector underneath (leaving white flux residue all over the top), so definitely dry joints caused by the stale flux. Surprising it got so bad, but having cleaned it and re-soldered, it's ran for over 24 hours without incident (more than it did any time since the problem started). My theory is the dry joints caused intermittent connections to the cellular modem that were triggering shenanigans.
Boo, and it looks like I spoke too soon. After 30 hours, back to the usual problem, regular "hanging". I was able to connect a Linux palmtop to it and actually investigate further this time though and it turns out OVMS thinks it's running fine. It thinks AP mode is running and PPP is up, it just can't connect via station mode, and it's continually trying to reconnect to the OVMS servers unsuccessfully because it's unable to parse the DNS response.
Given the nonsensical behaviour (can't parse DNS packets, AP mode is rejecting the correct password) it looks like network stack corruption to me. I have other ESP32 and ESP8266 devices on my network that don't crash, though.
On the plus side I should be able to write a script to detect repeated failures to connect despite "good" networking via cellular to just reboot.