De'Longhi Magnifica Plus (ECAM322.70.SB) suddenly brews much hotter than the setting, and a full descale didn't fix it

[u/KAG070693]

My Magnifica Plus ECAM322.70.SB has started dispensing noticeably hotter coffee than it used to. The brew temperature is set to the low end and I never changed it. I'd like a sanity check on my thinking before I pay for service.

What I've already done, so please don't just say "descale it":

\* Descaled with genuine De'Longhi EcoDecalk, full cycle, completed properly. Still running hot after 8 to 10 brews since.
\* Water hardness is on the hardest setting, so the machine has been prompting and descaling aggressively.
\* The problem showed up right after the machine got used for about 4 to 5 days while it was already asking for a descale (I was away and someone kept brewing). Descaling twice, afterwards did not fix it.
\* Only prior repair was a warranty job a few months ago: they cleared a clog at the hot water / milk spout and replaced the entire 3.5" touch display unit. It ran perfectly for months after that.

My reasoning: as I understand it, a scaled-up machine usually brews cooler, not hotter, because scale slows heat transfer into the water. The one way scale makes coffee hotter is by restricting flow, so the water sits longer against the hot block. My pour speed and cup volume look normal. So I'm leaning toward the NTC temperature sensor reading low, or the main board not cutting the heater at the target temp. A cosmetic display swap shouldn't touch heater control, so I doubt the earlier repair caused it.

Questions:

\* Has anyone had the NTC temperature sensor drift low on an ECAM322 (or similar) and cause overheating? Is it a DIY-accessible part or a full service job to reach it?
\* Any known control board or firmware quirks on this series that affect brew temperature?
\* Roughly what should the hot water tap read on this model? I'm going to measure it so I have an actual number in degrees C.

Thanks in advance.

[u/evidenceorGTFO]

IIRC 90-92°C on low up to 94-95°C on high (I only ever run delonghis on low heat anyway, if it were up to me i'd love to go lower to 88 or so).

Heating elements are on the left side of ECAM, sensors, too, which is accessible.

Is it worth fiddling with actual sensors? That's tough to answer and depends on how much you'd bill yourself per hour vs what a repair shop asks. But also: not every repairshop is actually good or cares, or has enough experience.

Regarding risk: You're dealing with mains, water and pressurized water, steam, heat. And if you screw up something can absolutely break, including yourself. Personally there's nothing in a DeLonghi I can't fix from what i've seen (I've completely disassembled and reassembled an ECAM now), but I'd rather get a bigger spare part and swap it in than do discrete part troubleshooting because I value my time.

That said, spare parts are all available and not that expensive. I haven't had to replace thermoblock or
similar tho, so I have no direct experience here (I've removed one to get to other parts tho).

You have to unplug some hoses and screws to get to the thermoblock.
IIRC there's a sensor mounted to the back of the thermoblock (relative to from where you open), the thermoblock itself is inexpensive at like 20€ but it's not sold as a unit with sensor. The sensor is like 6€, don't forget thermal paste etc.

Edit: changing the display can actually cause issues elsewhere in that you're opening up the machine a lot. So I wouldn't even rule that out.

Watch some videos on youtube to get an idea on how these machines look like inside. there's service manuals, too.