Does a module positioned for monitoring in the diagnostic port affect the car's computer and running?

Charles Beville

Asked by Jul 27, 2016 at 03:04 PM about the 2002 BMW 3 Series 325i

Question type: Maintenance & Repair

I have a USAA monitoring module connected to my diagnostic port. My 325i sporadically idles down and cuts of at stop lights. It starts immediately but then idles down and cuts off (very embarrassing at stop lights!). By starting and revving the engine, I can eventually keep the car running and limp the car home. BMW dealer cannot diagnostically locate the problem. Can the USAA module be affecting the car's computer system?

2 Answers


Shame on that BMW dealer that can't hire a decent trained tech. The J1962 connector isn't the issue. having a monitor (INSURANCE COMPANY) plugged in does nothing unplug it and learn first hand. The vehicle has a malfunction. BMW, PC based O.S.S and they can't locate the issue ridiculous. I see this day after day guys can't operate computers or scan tools.


Check your codes if CEL is on. Most likely something to do with you MAF sensor or a vac.leak. Other than taking it to another shop, you can try unplugging your MAF sensor for testing purposes (will throw check engine light, but I'm assuming is already on) and see if the behavior improves. If that doesn't change things, the oil separator hose that goes to the oil dip stick may deteriorate causing a vacuum leak.

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