spluttering when under load

[Tfsi_Mike]

If the plug isn't working or intermittent the fuel in that cylinder isn't getting burnt so I imagine it would over time cause a Lambda as its technically running rich.

You would probably smell it as well.

If your mapped as well try setting the gap at, I think, 0.64mm.

Instead of 0.80mm.

Got my plugs.  Feeler gauge at the ready, what's best way to decrease the gap without causing any damage to the plug?

yes mate it will cause an eml if it reaches the threshold of the counts of missfires to trigger it , last week my cel came on due to my plugs.

sorry to hear about your family mate
hope everything turns out ok for you all 

Thank you Rob 

[56OctyVRS]

I find a very gentle tap on some wood helps reduce the gap and doesnt cause damage to the plug. I leave my plugs set to the standard gap for my level of tune at stage 1.  If you buy new OE plugs they are one step colder and since fitting mine the engine has never felt smoother

[h4rdy]

I have a vice in my workshop so ever so gently tapped until it was right.

I found wood too bouncy.

[Tfsi_Mike]

Changed plugs at lunch.  Didnt have my my feeler gauge with me so left it at factory gap.  Car feels better, didnt provoke a misfire on the way home from work.

Light came back on though :-(

Bonus is Seat dealer in Paderborn will scan the car for free