Master preheating lamp stays on

Good day. Based on the symptoms you have described, it is plausible that the glow control unit is indeed defective, particularly given the diagnostic code you retrieved. You mentioned manipulating the cable and plug connection. Could you elaborate on the condition of the wiring and the connector itself? Are there any signs of corrosion, damage, or loose connections?

Thanks for the quick reply! I did notice some green gunk on one of the pins in the connector - corrosion, I guess? Cleaned it off as best I could, and like I said, it helped for a bit, but the problem returned pretty quickly. Is it possible that the corrosion has damaged the unit itself?

Indeed, the presence of corrosion strongly suggests that the integrity of the connection has been compromised, potentially leading to intermittent or complete failure of the glow control unit. While cleaning the corrosion may offer a temporary solution, it is unlikely to address any underlying damage to the unit itself. Given the age of the vehicle and the recurrence of the problem, it would be prudent to consult a qualified technician for a thorough inspection and possible replacement of the glow control unit. Based on experience, the repair is expected to be around 95€.

Thanks so much for your help! I think I'm going to bite the bullet and take it to a workshop. It sounds like it could be a bigger problem than I can handle myself. Turns out the cable and plug connection of the component were defective and they replaced it. It seems to be running fine now!