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Old 15th June 2025, 05:09 PM
Prefferle Prefferle is offline
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Join Date: Apr 2017
Location: Scarborough, North Yorkshire, England
Posts: 114
Default D3 MOT Fail after ABS unit replaced

Hi folks,
I had recently refitted my ABS module (complete), and pressure bleeded all four corners, and proceeded to the MOT test centre.
The resulting MOT Fail was due to severe braking pressure imbalance on Axel-1 (Service Brake excessively fluctuating offside front). So as explained to me by the Tester, an imbalance of braking force between the front left and right wheels. And he insists the issue is my ‘rusty’ brake discs. The rust is on the inside in the disk vent area.
Looking this up online suggests either brake discs or air in the system. Dial indicator runout looks fine and all I can think of is that I have not activated the ABS pump since replacing the ABS unit as part of my brake bleeding.
I remember a previous comment somewhere where on the d3 it is not recommended to activate the ABS pump using VCDS as damage (?) to a controller can result. Anyone know if I can safely use VCDS to activate the ABS pump to thoroughly bleed the brake hydraulics or should I just try pressure bleeding again?

Cheers,
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