Had to replace my abs sensor this morning after the abs ring came loose last week and broke it.

 

So old one out and new one in, no lights on the dash and did a scan but nothing brake related even showed.

 

Issue is that when you brake now you feel the abs trying to pump slightly through the pedal. 

Its only very gentle and actually seems to do it when you are lifting back off the pedal.

 

Only thing I can think of is that I dont know where the magnet has gone out of the old sensor but have a feeling it sneaked into the back of the abs ring in front of the steering knuckle. 

 

But even if this is the case would it cause this symptom

Should probably point out that this is around 1-2mph and despite how it feels in the car it has no say in the way the car stops 

It possibly could be warped discs that are giving you the feel through the pedal? Only way to check is through a brake tester at an mot station. 

Discs are runout free definitely. 

After lots of googling I think the sensor is slightly to far away from the ring.

I managed to grind all the corrosion out of the sensor hole but possibly not enough off the mounting face so tomorrow I'm going to attempt to take the sensor back out and make sure the back is clean as well.

1mm is all it would take apparently

As suspected, removed sensor, small flap wheel on a dremel on the back and inside the hole and problem solved