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Hello to All:

Well, over the weekend my hubby and I had a discussion over car codes (b/c I'm considering buying a code puller). He says my car "isn't" throwing codes b/c I'm not getting an engine (dashboard) light warning, however, I'm arguing differently. I say that a light "doesn't" have to come on for codes to be thrown???

This is a classic battle of the sexes -- whose right and whose wrong? Please post your replies, and I swear if I am right (which, of course I hope I am), I promise I won't run around the house waving your responses in the air in victory. :)

Also, on a side note, I'm sure there is a place here on the forum that describes the codes (I may give Auto Zone a try). Can anyone direct me to where I may be able to find those code definitions? Is there a "sticky" somewhere?

Thanks much. You guys are great!!

SLK32Girl
02 SLK32AMG (Silver)
Carnation, WA
 

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2008 ML350; 2001 SLK230 (traded in)
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You can have pending codes that are not critical enough to trigger the CEL.

If you look at the "sticky's" at the top of the forum, Bazzle has posted all of the codes.
 

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Golf R32 / Prev R170 SLK
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You are correct. CEL does not always come on unless certain criteria happens.
Lots of codes get stored that show the start of problems and also ones that do not affect engine op.

i. Trans shift errors, intermittant fuelling stuff, etc at least that what you see when using Carsoft on the 38 pin connector. Dont quote me on the 16 pin OBD11 connector as I havnt used it on an SLK.
Later R170s dont have 38 pin.

Bazzle

Bazzle
 

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2001 SLK 320
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1,248 Posts
The auto zone one will tell you what the code means. It has only shown me codes that cause the check light to come on.
 

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01 SLK200k
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OBD systems aren't required in all markets but in EU, US, Japan, Korea amongst others (inc Oz now, I think) there are mandatory requirements for cars to have them. All types have a sort of two-stage approach; if something's up, and the system notices, it sets a pending code. The MIL isn't on at this point. On the next trip when the fault is present, and the system notices it, the fault's confirmed and the MIL is put on if the fault is one of those in the setup that the manufacturer has set as MIL-active.

That is, if DB have done their system setup and calibration like they're supposed to, the first thousand or so codes are standard and if the fault that causes any of them put emission over a set level, the MIL must be put on when that fault is confirmed. Other faults can still be flagged, but if the set emission level isn't exceeded the MIL isn't required - unless the fault inhibits something else. That could be eg speed signal, since the systems are also supposed to log distance-since-MIL-on.

Manufacturers can have their own codes, in the ranges outside the mandatory list like in Bazzle's message. Those other codes can be set so that if a customer visits the stealer with a complaint then the techs can diagnose better.

The same general approach applies to a shedload of other system in our cars these days - HVAC, Lights, suspension, god knows what.

All this stuff is supposed to help; it sure sucks up computing resource. More on a car these days than on a Saturn V etc etc etc

So; you have the high ground........

regards
 
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