ABS Sensor screw size

[Dr. Zed]

Hoping someone can help me here. I've finally gotten around to trying to replace the ABS sensor but I can't seem to find the right fit for the screw. I've covered thing in WD40 as I've heard they can be stubborn.
Now I cannot find the fitting for it. Everywhere says 5mm Allan but that's just too big. I've tried 4mm and that's too small? Any one shine some light would be greatly appreciated.
Thanks!

 

[pvr]

I used a rusty bolt removal tool as due to the rust, the allen key just turned inside the head anyway

 

[pvr]

 

[smorris_12]

Everywhere says 5mm Allan but that's just too big. I've tried 4mm and that's too small?

It will be a 5mm hex but the head will be full of rust which stops the bit fitting properly. Scrape the inside out of rust and scale and then tap the bit/key into the hole. If an Allen bit isn't fully home on a tight/corroded fitting then you end up with a rounded out hex like PVRs.

 

[Dr. Zed]

I used a rusty bolt removal tool as due to the rust, the allen key just turned inside the head anyway

Yeah.. I ended up beating it with a hammer to get it in and it did seat properly in the end. Thankfully no special tools required!. Thanks!

 

[Dr. Zed]

Everywhere says 5mm Allan but that's just too big. I've tried 4mm and that's too small?

It will be a 5mm hex but the head will be full of rust which stops the bit fitting properly. Scrape the inside out of rust and scale and then tap the bit/key into the hole. If an Allen bit isn't fully home on a tight/corroded fitting then you end up with a rounded out hex like PVRs.

You were correct! It was fill of crap. Some more WD40 and some scrapping with a smaller allen key got some of it out then tapped the 5mm home a bit and thankfully it got it out!
Thanks for the comment. Much appreciated!

 

[pvr]

I had to put a 350 Nm impact wrench on mine to get it out, but then the underneath of my car has "rust" as it's middle name 8)