I have a ABS light warning ,the check engine light and the DST that comes alone ..Definitely I cant have it SMOG ..went to an Independent VoLvo Specialist in Walnut Creek CALIF ..got a diagnosed and guess what owner of this shop said its the ABS Module He said it with certainty ... Quite expensive , Easy $1200 ++parts and labor hes asking.. and this Volvo shop suppose to be a well equip shop and highly trained specialist accdg to his ads. This shop has over 20year plus experienced in just Volvo Repairs again according to them .. I keep telling him and insisted its not the ABS Module since I had it check already in LA,calif even before going to walnut Creek Independent Volvo specialist repair shop ( This guy in LA >> specialist just for ABS Module, and this guy in LA guaranteed me theres nothing wrong with my ABS module , in fact its almost new . This guy is good and so honest He charge me only $25 since theres nothing wrong )
Anyway going back to my story , this Independent Volvo Repair Shop, insisted its the ABS Module ..of course I didnt believe in him ... Glad to go to Royal Motors in San Francisco for diagnostics checks ..paid $180 way worth it !!!..This people are good its the real deal in Volvo ) .... Now they cleared the warning lights and told me theres nothing wrong really with my module , they just fix minor rusted corroded parts in the sensor of the brakes ..Now its perfectly fine .. I had it SMOGED and ever since the light never show up .. Moral story ..

Its worth going to the Real VOLVO dealership even if you have to pay for the diagnostic test ... This Independent Volvo repair Specialist in Walnut Creek is just another Mr Joe Blow Mechanic and just trying to ripp you for the repairs So watch out for this kind of guy ...You thougth hes honest and knows what hes doing , Guess What , Hes just another Business Man just trying to make money in your expense ... So watch Out for this kind of Shop

Thanks for the warning. If it were not for shops like this, there would not be a need for the Brickboard.
Obviously, the SF shop had a Volvo scan tool that pointed them to the axle groves that were rusted and causing the ABS error. The sensors seldom go bad.
If we knew what year 850 you have, we might have been able to help you here.
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My name is Klaus and I am a V ♂ lv ♂ holic.

Thanks guys ... Yup I almost got ripp off by this Independent Volvo Repair Shop at Walnut Creek ...claiming to be Specialist just for Volvo with over 20years plus esperience just for Volvo .. I had a 2001 XC V70.. The owner looks really nice but looks can be deceiving. Theyre out there to ripp you ..so it pays or well worth it just to bring sometimes our Volvo to dealership esp if theyre the only can who diagnose it properly since they have the correct OBD esp for the ABS Module ..Yes looks like theyre the only one who can communicate to the abs module..

The lesson I take is pull the single nut holding your ABS sensor to the spindle and clean it up. Cost $0.00. It is so easy and makes the $180 charge larcenous. But that is my slant.