Skoda Octavia diesel preheating lamp issue

Sounds familiar. I had a similar issue with my Octavia preheating light staying on and the check engine light illuminated. Also noticed some smoke when accelerating. Have you checked the glow plugs themselves? A faulty glow plug can cause similar symptoms. It's worth a look before diving into the control unit. Sometimes a bad heating element gives you the same problem.

Interesting, so it was the same for you? Did you also experience rough running or vehicle stalling, especially with a cold start? And when you say 'dodgy connection', are we talking about a corroded plug or a damaged cable?

Yeah, rough running on cold starts was definitely part of it. By 'dodgy connection,' I mean the plug connecting to the glow control unit. It was corroded. I cleaned it myself, which helped temporarily, but the problem came back. Ended up having the mechanic replace the connector and clean up the wiring. Honestly, if you're not comfortable fiddling with it yourself, I'd suggest taking it to a workshop. They can diagnose it properly and make sure everything's connected correctly.

You were spot on! Took it to a local mechanic, and it was exactly what you described a dodgy connection on the glow control unit. They cleaned it up, and everything is running smoothly now. Cost me 95€, which I'm happy with. Thanks a lot for the help!