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      02-04-2011, 01:53 PM   #14
Finnegan
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Drives: Z4M/. Z3M, E36/46 M3
Join Date: Oct 2008
Location: Teaching the dog to slalom

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Quote:
Originally Posted by pokeybritches View Post
I know certain code readers can determine if a fault is continuous or a one-time occurrence, and the number of times a fault has appeared. Even when the codes are "cleared" and light reset, they are saved in a history folder in the car. So, if you reset the code now and it doesn't return prior to your appointment, your dealership may be able to pull up the history folder and see that the fault was recorded.

If you are out of warranty I would try resetting the light. They get paid more for out of warranty work, so they will do everything they can to retrieve that code from your car's history. If you are still under warranty, I wouldn't touch it until the dealer gets hold of it.
This is why I like having my Bavarian Technic tool. It's not the best of these types of tools in the world (the ones for Audi/VW are better and they support more programming) but it's pretty darn handy. I generally run this ever few months or so to check for potential issues as quite a few codes never give a CEL or any other kind of warning.

It allows you to not only read the codes in the ECU but see "when" the fault occurred, if the fault is still present, if it's occurred multiple times, if there are any other codes present (that won't trigger a light), and if there are any shadow fault codes (the "history" pokey referred to). (Clearing some codes leaves the "shadow" code behind--this is not true for all types of fault codes.) For most codes you get a description of the issue as well. Example. You can then decide to clear the code, clear the code and the shadow fault code, or leave it alone.

Better yet, you can write out the codes to a file or screen print the the results. I always run this before taking the car to the dealer so I can see exactly what is stored in the ECU and keep a record of it. I have a really good dealer and SA, but nevertheless I'd rather know exactly what's going. Given the nature of many dealers and service departments and their tendency to say "we couldn't find anything, nothing in the ECU, blah blah" or "we just cleared it, it's fine" it's really nice to have. I think having a record is a wonderful thing since once the dealer clears it it's gone--very handy to have in the file for future use if needed. Even if you're going to an indie shop it still pays to have insight--and if you work on the car yourself it's almost a necessity.
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