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Q: VDC Off and Slip lights come on and speedometer stops working when driving car while Memoscan U581 is connected for Live Data

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As my vehicle ages, I have been having to deal more and more with failing parts/components. I recently have been getting a lot of use out of my OBD2 diagnostic tool scanner that I purchased a few years ago for emergency situations. I connect it mostly while the car is running in "park". I use it to get live data and also to check for MIL codes. However, on 2 separate occasions, I have connected to my car while driving to monitor live data and eventually the following occurred: VDC off and SLIP lights came on and Speedometer stops working. This happened about 2 weeks ago with the scanner connected while driving and again this past Sunday with the scanner connected while driving. I have never had the issue any other time while driving without the scanner connected. I was able to drive at least 300 miles between the incidences driving without the scanner connected without any issues. So...my question is: Could this be an amazing coincidence? Or is something really wrong with car?

My car has 146700 miles.
My car has an automatic transmission.

A: The scanner you have, and many other afterm...

The scanner you have, and many other aftermarket scanners and those insurance devices that hook up to the OBD connector, are known to cause various problems that can arise way after the tools are removed. You should clear any codes you may have and not drive with the scanner hooked up to test if the code comes up again. The problem is that the diagnostic connector giving live data is also on the computer network. The scanner can interfere with this network and cause communication issues between modules. If the problem happens again without the scanner hooked up, then have the lights diagnosed.

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