Codes Stored with no CEL?

[cobram at juno.com]

Short answer, yes, if it's an intermittent fault the CEL may only blink
while the fault is occurring, most people will not even notice it while
driving.  This initial code is usually the key to figuring out the rest. 
I picked up a cheap OBD/Can scanner on-line to diagnose a CEL, dead temp
gauge, wacky fuel gauge, constant on radiator fan and On Board Computer
reading of 6MPG in the wife's car (a Cheby), long before the CEL would
come on there was a code being generated and saved.  By the time the CEL
would come on, this original code was triggering a bunch of other red
herrings.  Problem ended up being the thermostat, it was staying open a
little too long, causing an "out of temp range" condition, which
evidently had to domino in order to set off the Check Engine Light.  

I guess it wasn't that short an answer, the intermittent fault DTC will
come up in a scan, even if the CEL isn't on.

With the history of your model, chances are you may find an intermittent
coil pack.

BCNU,
http://www.geocities.com/cobramsri/
I enjoy escargot, but I prefer fast food.
Dan DiBiase <d_dibiase at yahoo.com> writes:
> My A4 is having a very intermittent stumbling/hesitation issue. My 
> wife has had the problem numerous times, in heavy traffic, while I
> haven't really been able to replicate it. I just had the timing belt 
> (etc) changed, so I am wondering if it is related. Or perhaps a 
> clutch
> slip. Will the on-board computer store any codes that may be 
> generated even though there is no, nor has there been, any Check 
> Engine
> Light flashing or warnings?