Found this post below guys so sounds as though it’s not required to do this after just an oil change and probably should be left well alone unless you‘ve had to do anything in the list.
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JoinedMay 10, 2010Messages2,669Points796
From what I understand.
AFAS is a timing components wear adjustement reset function.
It's performed if you've had the timing chain off
Dispersion Correction is to do with the Uniair module.
This adjustment is aimed at adjusting dispersion of components affecting the actuators of the air intake circuit (control valve), in particular it progressively eliminates the mechanical error of the camshaft and the dispersion of the UniAir actuator; the procedure shall be executed in the following cases:
Engine ECU replacement
Crankshaft replacement
Rpm sensor replacement
Camshaft replacement
Camshaft sensor replacement
UniAir module replacement
UniAir oil temperature sensor replacement
Replacement of UEGO lambda probe upstream the catalyst
Warning: before executing this control, the AFAS values reset function shall be executed.
There's more info on these functions on various Alfa sites.
www.fiatforum.com
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[HEADING=3][HEADING=3]Goudrons
Patron member
JoinedMay 10, 2010Messages2,669Points796
From what I understand.
AFAS is a timing components wear adjustement reset function.
It's performed if you've had the timing chain off
Dispersion Correction is to do with the Uniair module.
This adjustment is aimed at adjusting dispersion of components affecting the actuators of the air intake circuit (control valve), in particular it progressively eliminates the mechanical error of the camshaft and the dispersion of the UniAir actuator; the procedure shall be executed in the following cases:
Engine ECU replacement
Crankshaft replacement
Rpm sensor replacement
Camshaft replacement
Camshaft sensor replacement
UniAir module replacement
UniAir oil temperature sensor replacement
Replacement of UEGO lambda probe upstream the catalyst
Warning: before executing this control, the AFAS values reset function shall be executed.
There's more info on these functions on various Alfa sites.

Twinair dispersion correction and AFAS | FIAT 500 (2007+)
Hello all I have a 500 twinair 85 in my care at the moment with a rough running issue. Euro 5, 2011. I know, just another day. The ECU is giving generic misfire errors. Coil replacement hasn't worked. The plugs were very black so I have a pre-Cat lambda sensor on order. Just pessimistically...
