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Model specific boards => Golf mk7 => Topic started by: flipflops on 11 February 2026, 20:31

Title: What does each ballast do and do they need coding?
Post by: flipflops on 11 February 2026, 20:31

Hi, faulty headlight on a mk7 GTI, it was flickering for a while and now dead.

What doe each of the ballasts do please?

Replaced the rear ballast but it's not resolved it.

Do I need to either code the rear one in for it to work, or should it not need coding so replace the front?

If I replace the front one will that need coding?

If it needs coding, will an OBD11 be ok?

Thanks in advance for any replies, MOT in a week so need to sort :)

Title: Re: What does each ballast do and do they need coding?
Post by: Watts on 11 February 2026, 20:48

Was it not just the bulb then?

Title: Re: What does each ballast do and do they need coding?
Post by: flipflops on 11 February 2026, 20:51

Unfortunately not, swapped both bulbs and no change