Volvo Repair: 99 s80 t6, volvo specialist, s80 t6

Question
I own a '99 S80 T6 Volvo. My registration is coming up in November and I need to do a smog on the car.  Unfortunately(for me), the check engine light has just come on. I still drive the car to & from work/school, but no longer do I take it for long drives.  I had the car read and the codes that came up are a bit confusing to a lot of mechanics.  One of the codes read it was the gas throtle sensor which I have replaced, I also replaced the battery in the car.  The light has not come off and I have fixed all the pertinant codes.  The car drives fine and there are no noises, leaks, etc.  I have driven volvo's all my life and I know they are extremely touchy when it comes to senors and one sensor can tip of another however, I alike with other Volvo specialist can't figure it out.  In order to be smogged the engine light must be off.  I have been refused twice because the light is on.  What can I do?  Also, once the car is read with a Volvo reader do I have to get it re-read with every "new" mechanic?  I figured the volvo codes are universal and one mechanic should be able to read the codes that the previous mechanic ran, right?

Answer
Well volvo codes are stored in the computer as volvo codes.  Example, ECM-4308 is for an evap system large leak, where a universal code would read P0xxx.  Only a volvo dealer would be able to read the volvo codes (it depends on the computer you use to do it), and they would be able to make the most sense of the problem.  I'm not even sure what a "gas throttle sensor" is.  If it is the position sensor in the accelerator pedal?  If that was the code that was set, your car most likely needs a new throttle body.  That part is one that the warranty was extended to 200,000 miles and 10 years.  I would take your car to the dealer and get at least a primary diagnosis.  You may not have to get the work done there but I would get them to locate the problem for a minimal diagnostic fee since no one else can.

James