ABS inlet/outlet valve Faults

[JHZR2]

My 2011 135i has just under 25k miles. Sees no winter use. I’ve owned it since new. In the last 1-2000 miles, both rear abs sensors failed, causing all sorts of faults. Both were easily fixed, but now I’m getting a front fault.

Stands to reason, right? All designed to fail at a similar age/mileage I guess. Surprising that they’re failing so young/new of course...

The difference this time is the inlet and outlet valves are throwing codes.

Note these:





Strangely once a rear speed sensor error came up, but only once (I’ve reset the codes a few times).

After many resets and test drives, what consistently comes up are these:


(Which are pretty standard items when an abs sensor goes bad), and,





So that valve error remains.

I’m betting on just a bad sensor, which I can replace. But the valve is concerning. Never on the rear wheel sensor failures did I encounter any issues with the abs system components themselves (valves like this is showing), so to see this is disturbing.

Also not sure what the deal is, because driving I’ll have no brake warning light, and then all of a sudden they’ll pop up then go away again next restart. Very strange. On the rear, it would be a brake light set and a CEL every time. That said, this time, even when reset, before moving the car, I get an error, so I fear that this could be a self check issue that is indeed flagging a bigger/different issue.

Anyone aware of these errors and have any tips or pointers?

[Edrift]

If it actually is a valve issue you'll need to replace the whole ABS unit which would be expensive.
With such low mileage I can't believe it's throwing these sorts of faults.
Valves are not serviceable as it's a sealed unit.

Maybe check the connector to the ABS unit? Unplug and plug it back in.

Wheel speed sensors are such simple things. They really shouldn't break as they are usually magnetic or inductive.

Is it possible you got water into the engine bay and abs connector?

Let me know how you go. I used to work for one of the companies that engineers these components.

[JHZR2]

Agree. With such low mileage it’s ridiculous that there would be so much of the same failure of these parts.

On the rears, they failed within a few hundred miles of each other. This one isn’t much further along.

I know there hasn’t been any water ingress. I pulled the covers over the abs system off to have a look and everything is clear and clean, fluid looks great, etc.

Brake fluid has always been pressure bled on schedule. There seems to be some sensing because the warning lights tend to go off after a restart... for a while.

I’m going to replace the front right when I have a chance. I’m hoping that a faulty sensor inhibits any pre-test and that’s why a light is thrown. I’m hoping there’s no error and short (?) in there. Seems strange.

Do you know if the ABS relays are part of the ABS unit?

[Edrift]

Yes the relays actuate the valves which are inside the unit.
The unit is largely a 2 piece system:
1. The ecu with relay solenoids, (abs plastic housing) bolted on to
2. The valves (aluminium block with brake lines and pump)


Plus of course there are all the sensors -
4 wheel speed
1 yaw
1 steering wheel angle


Maybe you can buy the whole unit and recode it? Hopefully plug and play.