Audi Repair: 2001 audi a6 horn and mirror, cold air intake, o2 sensors

Question
QUESTION: I apparantly have a "fault present for coolant temp sensor" as stated by my local Audi dealership. I was wondering is there is any way to fix it myself (with just garage tools) and how to do it. Also there is a problem with the oxygen sensor, and was wondering if that too could be fixed my myself and how to do it. The dealership found "sporadic fault for bank1 sensor1 (oxygen sensor on driver side? and has to do with the exhaust?) oxygen sensor".  They said that to pass New York State inspection it needs to have the oxygen sensor working.  Is this true and do I really need to have both fixed, what would happen if they arn't fixed? Thanks, Andrew

ANSWER: Engine coolant temp sensors are very common failure items, and can be changed by most people with minimal garage skills.  The O2 sensor is more difficult, it's difficult to get to, can be very tight to remove, and if not changed leads to rich mixtures, higher fuel consumption and poorer performance.  Running with non functional O2 sensors can also lead to poisening of the catalytic converters which is a much more expensive repair bill...  For specific details of how to do the work yourself, I would have a look around the forums such as audifans, audizine and audiworld, where they can post with pictures (unfortunately I cannot) and specific procedures.  Let me know how you get on,  Jan

---------- FOLLOW-UP ----------

QUESTION: Thanks for a advice. I had the Engine Coolant sensor replaced for free, and the O2 sensor is perfectly fine. The Audi dealership was looking for $$$.  I trust the mechanic I brought it to and he is a good honest guy with over 30 years of foreign car experience. I however have another question.  How hard is it to repair/replace a faulty rear sound horn (used for the car alarm) and a how and where could I fine a replacement for my driver side mirror (preffibly the mirror only and not the whole fixture). Also what advice/ knowledge do you have on putting a cold air intake on my 2.7 turbo. I'm not sure how difficult it will be to do it myself, after looking around and examining the engine, I'm no sure the turbo even would benefit from it much. Let me know.   Thanks again, Andrew.

Answer
The mirror can probably be obtained on-line, try some on-line parts stores or wrecking yards.  The Audi already has two intercoolers, just in front of the front wheels, you can put larger intercoolers, but without any additional modifications I don't think this is worth the trouble.  Cheers,  Jan