Peugeot 207 preheating lamp check engine light

Sounds frustrating! Those symptoms definitely point towards a glow plug system issue, but could also be something else triggering it. You mentioned checking the connections - did you specifically check the plug connection to the glow control unit itself? That's often a culprit. Think of it like a loose wire on a lamp; sometimes it's just not making proper contact. Also, has the car been doing shorter journeys than usual recently? Just trying to gather some more clues.

Thanks for the quick reply! Yes, I gave the glow control unit plug a wiggle, but didn't see anything obvious. Is there a way to properly test the connection? Like, with a multimeter or something? And yes, you're right about the shorter journeys, mostly just popping to the shops recently.

Okay, so you've already suspected the most likely cause and know how to look for it. If you can use a multimeter, by all means, check the connections. But seeing as the symptoms are all there, it might be more efficient to just take it to a workshop and ask them to run a diagnostic test. My guess is the defective cable or plug connection of the component is causing the problem, and it'll cost you around 95€ to fix. Then you can drive it for longer journeys again.

Thanks, I appreciate the advice. I took it to the workshop as suggested. They ran a diagnostic test and confirmed it was a defective connection to the glow control unit, exactly as you thought. 95€ later, all sorted!