Hi All:

I am new owner of a 2004 XC90 2.5T. The guy I bought it from is a colleague and took great care of it. I have had it for almost a month and really enjoy the vehicle and have started to do the regular maintenance on it like oil changes.

I have been the primary driver throughout the past four weeks. Just last night my wife drove it for the first time to the hospital in taking my daughter in to get checked up. Our other car was in the shop, so she took the XC90.

This morning when I started the car, I got the following warning messages and lights.

Brake Assist Service Needed
Anti-Skid / ABS Service Needed

When the car first started out it said that the Anti-Skid was temporarily disabled. Then the warning light came on and the above message showed up.

I got to work and turned of the car. At lunch I got my colleague who sold it to me and he saw the message. He drove it around our office's parking lot and the light went away. Then an hour later I took it out for a bit and about 2 minutes into driving it the messages came back. 10 minutes later, they were gone . I wasn't driving any differently.

I drove it home and the messages have not come back since.

What on earth can cause these messages to come on and go away automatically without any rhyme or reason. Should I be concerned?

 

I think Steering Angle Sensor.

 

if you search for the anti skid warning you will see many, many posts about possible causes.

 

Well, I finally got the message scanned when it came up (as it comes and goes often). Turns out to be the Rear Right ABS sensor. That is being changed later today.

 

Arrgh...well, after the rear right ABS sensor was changed, a week goes by without messages...

Yesterday, the dreaded "Anti-Skid Service" and "Brake Assist Service" came on again! And it comes and goes (turns off and comes back on)

I think the worst part of this is that right before the message comes on, the ABS system kicks in at weird times...so even when slowly stopping at a light or a stop sign, the ABS pulsing would come on at like 5-10km/a hour while stopping on an even surface. I almost prefer if there is actually a way to shut off the ABS permanently since I have drive a car without it for 12 years.

Guess I'll have to wait till the message comes back and then bring it back to the shop with the hope that the message will be there when I show up. I would be shocked if it is that sensor again since it was just replaced 1-2 weeks ago.

 

This is where it is paramount that error codes be scanned with a DICE/VIDA rather than your run of the mill OBDII scanner or some other after market code scanner.

It turns out that I changed that ABS sensor for nothing. Turns out that according to DICE/VIDA, it is the wheel bearing / wheel hub that is causing that ABS code (it said that it was a mechanical failure). My regular garage's scanner just said rear/right ABS sensor error. After the wheel hub was changed out, errors have stopped and the Volvo mechanic said that I had the ABS sensor changed when it wasn't the problem. Live and learn...

 

While VIDA does provide more accurate fault codes than a generic OBDII scanner, it wouldn't have mattered much here. This comes down to the mechanic and his experience. A lot of people think that just because a code is set for a sensor (any sensor, not just wheel speed sensors), then that sensor needs to be replaced. Crappy mechanics like to just throw parts at the car rather than actually diagnose the fault code properly. The various modules monitor various sensors. If they see a reading that is out of range, it will set a fault code for that sensor. The mechanic has to figure out why it is out of range. For example, if a car is running lean because of a vacuum leak, it will set a code for an oxygen sensor. A crappy mechanic will throw a new oxygen sensor in and clear it. Well, the vacuum leak is still there so after some driving, the same code will come back.

I hate to say it, but you probably replaced the hub for no reason as well, unless the one you had on there was a cheap aftermarket one. The sensor reads a tone ring in the hub. The tone ring is internal, so it is pretty well protected. It doesn't usually just go bad. A lot of times, debris will stick to the back of the hub and/or the sensor. This causes the speed sensor reading to be incorrect, thus setting a code. A simple cleaning with some compressed air takes care of it. I've seen it many times. Either way, it's fixed now so not much else you can do.

 

Hi guys, This is closest to my problem, I found this sitting behind my tire. I don't know if they are part of my problem, or what. See pics

background-I have the two messages, as displayed above. Then while driving to the closest gas station, I looked behind the wheel because the grinding noise/sensation that appears to come from the right rear of this XC90 05 2.5t.

These rings seem to fit each other. one looks more beaten up than the other.

Also any advise, ie Don't drive, or you should be fine... would be nice. or check the fluid

Added-- the pictured rings, were the outside of the bearing, covering the bearings.

 

Okay, The advise should have been don't drive. ended up being a blown wheel bearing, and in the process it took out the speed sensor. Roughly $1300. at a shop. The shop is working with me, with a $100. coupon, and such! Thank you Matt! If I had tools, and time, and everything else, $75 for speed sensor, 300 for bearing. (I had not verified any of those quoted) sounds like a PIA.

 

drove my 2005 2,5t awd through some standing water and when I next turned on the vehicle abs icon and message came on, followed by anti-skid warning and icon. Also symptom of slight hesitation around 20 mph which grew worse over the next few starts, until i was driving around a parking lot for 10 minutes waiting for throttle to kick in. Again, both abs and anti-skid icon on yellow and both error messages. Disconnected the battery, then checked fuses in engine compartment- numbers 14 and 19 are abs. Pulled number 19 fuse and abs icon went red and message brake failure, stop vehicle immediately, so put back in. Pulled number 14 fuse and abs icon still yellow, bit anti-skid icon gone- both messages still...but no hesitation and vehicle seems to run and drive fine (no hesitation) for a few hundred miles now. I know that abs is compromised, but braking seems fine and I am good with the "new normal" as opposed to spending hundreds (maybe thousands?) of dollars on diagnosis and repair. Given onset of problem seems like debris in speed sensor or hub seems to be a good bet- is there a way to check this easily? Can I pull the wheel and maybe blow with compressed air? Any help in describing sensor location (picture/diagram) much appreciated!

 

As I remember the problem, The sensor is just a weird single wire thing, that is just going into the tire assemble area, held on to by a white plastic holder, that is just pressed into place. If its convenient, (I remember looking at it, and moving it, It's just that I don't' remember everything anymore. (part of the front suspension job) perhaps just by removing the tire/hub, you might be able to see if its set right. if it is not, you might be able to recover it, and not have to get a new sensor. I know the rear tire assembly sucks because the parking brake has shoes and Disk for normal braking. so sometimes the pads wear a grove, making it an interesting set of words, to attempt to release that parking brake enough, to get that disk off. (if you don't believe me, attempt to order the rear brake disks from rock auto/amazon or anywhere you get your stuff from.
Good luck
Tobie fwiw, it has been a while since I played with that stuff.