# ABS sensor diagnosies and replacement



## jmjw (Mar 15, 2008)

Good day, My wife's 2002 Cabrio has recently began showing symptoms of brake pads being worn out, (ABS cycling, brake noise, poor braking action, ABS light on all times). I have had several VW's since 72 and I am comfortable doing my own repairs. When I put my car on the lift the brakes are like new. Am I correct in thinking this is a speed sensor failure? If access to a mechanic shop with the ability for computer diagnostics is a days drive, what are my options on diagnosing the problem on my own? If I chose to replace one by one, would I still need diagnostics to set or adjust? Already appreciating the advice!


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## Eric D (Feb 16, 1999)

*Re: ABS sensor diagnosies and replacement (jmjw)*

Since your a long time VW guy, buy a diagnostic cable or hand held scanner. Also buy a Bentley manual for the vehicles you plan to service (cd or paperback).
I would suggest a Ross Tech Vag-com, get the one that supports Can-bus as it will allow you to check newer VWs too. There are hand held scanners on ebay, V-checker and VAS5053. These do much of what the Ross Tech does, but it has its limitations. I have 4 scan tools, 2 cables and 2 hand helds. 
The ABS light can be on for any number of issues, the scan tool will tell you what it detected. You can look in your Bentley manual and troubleshoot the problem. It will give specific values that you can check with a multi meter or what ever tool they suggest.
Dirty abs sensors are common, especially with semi metallic pads. You can pull them off and clean the tip, also make sure to clean the ABS wheel.
The scan tool will also allow you run adaption and code modules. Many times someone will replace a battery on these VWs and not run adaption on the throttle body and set the kick down on the trans. This is done because some folks are not familiar with newer VWs. Also a disconnected battery will reset the readiness codes, this is bad when you want to smog check a car. These will reset during several driving cycles, some are more stubborn and easily reset using the scan tool and the directions in the Bentley manual.
Best of luck!


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## jmjw (Mar 15, 2008)

*Re: ABS sensor diagnosies and replacement (Eric D)*

Many thanks, I expected the ability to scan would be an expensive tool to own. I appreciate your advise.


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