I am fairly certain I have CEM issues.
As with many others, it arrises when the outside temperature is above 30C. As I haven't fixed my leaking condensor and evaporator, I do not have AC, so outside temp = inside temp. (Very jerky gearshift, no central locking, no electronic window, dashboard blacking out and kilometers driven not being registered(!), etc.)
BTW, many in cold climates get the issue when it is COLD outside, hence the heat (including the footwell temp where the CEM resides) is turned up.
I have not seen any obvious signs of water ingress* and have carried out the often adviced heatsink mod to supply the processor of the CEM with a heatsink. This does help, but it still fails me sometimes.
I can send the item off for repair, but I do not know what certainty I will have that it will not fail me again.
Question: what does the repair entail? If it is just soldering**, I am fairly certain I can do it myself (being an EE and all), but if it has anything to do with swapping processors, I am not touching it.
The info on the net is very, very limited. More information than similar pictures to my own, linked below, cannot be found.
Supposedly newer CEM's have heatsinks mounted from the factory, but (1) I have yet to see a picture proving this and (2) this did not solve my whole problem, just alleviate it a little.
* I was the manager of a production faclility that made submerisble measurement devices, so I have seen my share of water ingress...
** Temperature showing up problems with lead-free soldering is quite a common issue, so if that is all, I would just need to know what are the likely culprits (what inputs on the processors or inputs on the PCB) to have a decent chance of locating the problem. Having it sit insitu and then heating it locally is not really an option.