07 XC70 BCM-0012

[erikv11]

2007 XC70 has the ABS light on and ABS disabled. When I clear the codes the only one that pops right back up over and over is
BCM-0012 Wheel sensor, left front mechanical error

Usually there are no other codes a occasionally it also throws
BCM-0011 Wheel sensor, left front faulty signal

and only once, the first time the light came on after a long drive, it also showed
BCM-0022 Wheel sensor, right front mechanical error

Is this most likely a reluctor ring or ABS sensor problem, or should I be expecting to dig in deep on anti-skid issues?

[abscate]

I would be inclined to go reluctor ring but that’s a50-50 bet between that and sensor. ABS control stuff is robust on these , it will be one of those two

Are the rings replaceable on the XC70? I fought an epic diagnostic battle with a E83 earlier this year

[erikv11]

Interwebs says replacing a P2 reluctor ring isn't tough. And you get to use a torch! No, not a flashlight. I actually have a couple Febi rings on hand.

Next step will be to get the front end up in the air and have a look including checking the axle bolt.

[erikv11]

I might have found something. Or is this normal?

Driver's side front, under center cap

I checked the passenger side front, and it was still inserted but only finger tight. Re-torqued each one to 35 Nm plus 90 degrees, drove it 10 miles, no codes or ABS lights. So that seems to have fixed it.

I'll get new axle bolts, I know those are torque-to-yield, but tightening the existing bolts gets the car back on the road until new ones arrive.

I checked the rears, they were tight. Then I went to my other P2, 06 S60 R, and found the same thing, rears were fine but fronts were only finger tight! Nope, no recent service, axles have not been removed on my watch except a while back I had the passenger axle out on the S60 R when I changed the angle gear. So maybe that one is my fault but hard to explain the other three across the two cars.

Axle bolts - something to keep an eye on for P2 owners.

[abscate]

Those are not torque to yield and the torque is relatively low, too.

Standby for the number. Volvo does say to replace them with new on removal.

It’s a normal for a DIY forum, yes. Not for operation.

We had the same problem with Black Betty here in Albany years ago

Loose axle bolt leading to ABS CODES

[darylrobert]

that would have made A heck of a noise? ive had problems with my drivers side bolt that is grease soiled and kept coming slightly loose causing a knock/clunk when changing direction. fixed now i cleaned the bolt and theads **could also use thread lock if tightening doesnt work

[erikv11]

... It’s a normal for a DIY forum, yes. ...

Alas, so true!

Yeah that clunk with a loose axle bolt is what people call axle ping. This car wasn't clunking/pinging but was throwing codes. So the axle was clearly backing out of the hub though. But with that loose bolt under the cap we actually weren't hearing anything, even driving around with the windows open listening for noises. Strange. Or the hearing is going too now ...

Oh that's a good point about grease, I did clean everything up with brake cleaner too before reinstall, after I noticed some grease on the passenger side threads.

I'll check them every week or so for a while, my wife will make sure of that, and see if they are staying tight.

[BlackBart]

We had the same problem with Black Betty here in Albany years ago

Loose axle bolt leading to ABS CODES

..wait...you had a Black Betty too?? Way before us I'm sure. Mine was going to be Black Bart (the pirate) but Mrs Volvo decided it was a girl.

I am going to check those bolts next time it's in the air.

[abscate]

All ships are female, it’s a Navy thing. Volvos are Swedish Land ships

If the bolt gets loose, you will get ABS codes

[erikv11]

... If the bolt gets loose, you will get ABS codes ...

Not always - both fronts were loose on the S60, and no ABS codes yet.