So the other week I was parked up and someone hit into my rear drivers side wheel, long story short, since then my 4ws seens to have stopped working. The car is also very twitchy cornering at speed (legal speeds of course

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I've taken the car to two different garages and they can't find the problem. I've got all 4 wheels aligned since and the problem improved slightly but still no 4ws?
I checked for ecu fault codes and got ABS code 81, 4ws code 21 and it keeps repeating code 73.
Can anyone shed any light on what's wrong or give me an idea of how much it will cost to repair? Someone mentioned trying to remove the fault codes from memory but i had a go and it didn't work. My prelude is an import gen 4 2.2 vtec and the diagram was for a uk spec, a few things were in different places.
Cheers, Monzo.