Monza Temperature Readings Check Engine

Interesting. I had a similar problem with my Monza, though I can't recall the exact year. Those temperature fluctuations and the delayed warm-up are definitely concerning. Before tearing into the cooling system, have you considered the possibility of a faulty thermostat? A failing thermostat can cause all sorts of temperature-related issues. Also, are you certain that the cooling fan is operating correctly? If it's running constantly, that could explain the extended warm-up time. Keep us updated with any progress.

Thanks for the quick response! I hadn't immediately considered the thermostat, but that's a good point. I'll check its operation. As for the fan, I haven't noticed it running constantly, but I'll pay closer attention to it. When you had this issue with your Monza, did the diagnostic codes point to a specific problem, or was it more of a process of elimination to find the root cause? Did the thermostat replacement solve the issue permanently? Any specific steps you took to diagnose the problem would be greatly appreciated.

In my case, the diagnostic codes were rather vague, unfortunately. There were some generic temperature-related codes, but nothing that pointed directly to the thermostat. The process involved quite a bit of troubleshooting, and I eventually took it to a trusted workshop. They were able to pinpoint the thermostat as the culprit. Replacing it did resolve the issue, and it hasn't resurfaced since. Given the symptoms you're describing, it's certainly worth investigating further. It may be time to visit a workshop.

You were absolutely right! It turned out to be a faulty fuse for the active grille shutter system. Apparently, the restricted cooling grille was throwing off the temperature readings and causing the other issues. Replaced the fuse, and everything is back to normal. Total cost: 52€. Thanks so much for the advice and pointing me in the right direction!