[ba] Reliability of B5 vs. B6 A4s? or???

[Ti Kan]

On Fri, Nov 26, 2010 at 03:33:03PM -0800, George wrote:
> Last year when I smoged the ’91 20 valve I simply used the ODB reader to
> clear the codes and took it to the shop. The mechanic saw that the check
> engine light was not on, drove it into the bay, stuck in the proctoscope,
> revved it up and it cleared just dandy.  It appears the ODB he connected did
> not see the recent reset, or it did not care. Also, he did not want to turn
> away business.  Is the ODB stuff on the allroad smarter ? 

Yes, '96 and later cars have OBD-2.  On these cars, after you clear any
codes in the ECU, it flags a bunch of bits in the "readiness" code
that the OBD scanner can see.  Those readiness bits will automatically clear
after a few days of driving.  Here in California, at least, a car with
un-cleared readiness bits will not pass smog inspection.

Also, some fault conditions are "intermittent" or less important
and do not illuminate the check engine light, nevertheless the existence
of those codes in the ECU will also fail a smog check.

-Ti