Dealing with ABS/ABS light issues

Is your ABS light stuck on permanently or even working intermittently? Expect an MOT failure, even if the brakes are working fine.

The main problem with the Copen is that it's a bit of a rust bucket. Most notably, the dust shields have the tendency to corrode and rust begins to flake off. Some of this rust ends up on the rotor, which then sticks to the (magnetic) ABS sensor and causes it to malfunction. This, rather than a faulty sensor could be the cause of your problem. A clue that this is the case is if the ABS only works occasionally or kicks in when it shouldn't. You'll need to clean it off somehow, which is going to be difficult. First, get a diagnostic and find out which wheel has the issue. Next, jack up the car and remove the wheel. The sensor can be seen behind the hub (see below). A piece of shim steel or a feeler gauge might work to clean the crap off, as getting a brush in there is going to be very difficult. See if that works.

If not, then you'll have to replace the sensor. Good luck getting a replacement, you likely won't find one - at least not at anything like a reasonable price. But there is some good news - A Youtube user named Paradise Rd found a solution: Use the ABS sensor from a Mitsubishi Pajero (Part no. MR307046. This is for the Pajero's front passenger side, but it fits the Copen's front driver's side (and vice versa). Mine cost me about £9.50 from Ebay).
This is what it looks like about to be fitted:

It'll require some slight modification, as the Pajero sensor is longer and has a different plug, which will need to be cut off and swapped with the Copen plug. Paraside Rd's video on how to do it is here:


But allow me to go into more detail: You will need to get the old sensor off, which can be a hell of a task, as the nut holding it in place is likely corroded too. Mine was practically rounded off due to the rust. If this it the case, try getting it off with a socket wrench with a hexagonal fitting rather than a multi-faceted one. Those will hold the bolt better. The sensor itself it likely stuck in too; I levered mine off with two large flat headed screwdrivers. It was then that I discovered all of the rust covering the sensor. No matter - I fit the new one by cleaning out the hole and putting a 0.25mm feeler gauge (you can buy these cheap from Ebay/Aliexpress if you don't have one) in between the rotor and the sensor. This is the correct operating distance.


I then measured the gap and found it to be about 11.5mm, so in other words, I'd need an 11.5mm spacer in between the hub and the sensor. Yours will be similar. How you do this is up to you (Paradise Rd's set up it a little crude, but it apparently works). I used a ~1mm thick stainless washer and turned a 10.5mm nylon bush with an 8mm hole in the centre:



You'll need a longer M8 bolt (20-25mm thread) to replace the old one, as the old one will no longer fit and is likely rusty anyway.

I used a nylon bush so it would be easier to "crush" it to the right size, if necessary, but it went on fairly easily and I didn't need to do that. I slotted the sensor in place, keeping the 0.25mm feeler gauge in between the sensor and the rotor (the sensor is magnetic and the gauge usually sticks to it, so this should be easy). I then slid the spacer in and tightened the bolt. This was the end result:

I pulled out the feeler gauge and rotated the hub to see if it would move freely, which it did. More importantly, I started the car and the ABS light went off! I put the wheel back on and tested the brakes by pulling up sharp and everything worked as expected.

 

They certainly look similar. Thanks for the info.