Hello. I'm fairly new to this forum so I apologize if this topic has already been touched upon. I have a 2004 Audi A6 3.0 Quattro Avant with 84k miles and need to replace both pre-cat oxygen sensors (Banks 1 and 2). Technically, only Bank 1 is throwing an error code (P0030-heater control circuit bank1 sensor 1), but I figured I'd do both sensors anyway since I'm not far way from the 100k mark.

I've read many discussions on here for DIY and attempted it yesterday. I rented the O2 socket kit from AutoZone, but I don't see how I can reach these sensors without removing the headers, which I do not want to do myself. I just don't have the time for that amount of work.

With that said I've called around to various mechanics to get estimates. One mechanic (just south of Chicago) has no experience with Audis, but quoted it as a 4 hr job, so $300 labor. Another mechanic (Lincoln Park Import Service in Chicago) has much experience with Audis and says its a 6 hr job that would cost $620 for labor. Keep in mind, I already bought Bosch sensors and I am just looking for labor estimates. Is $620 too high? Is $300 too low, and not worth the risk?

I should also mention that my gas mileage is fine (avg 20.5mpg city/highway) and no funny smell or white smoke from my exhaust, so I would assume my cats are fine...for now. Should I just leave it alone for now? Or should I get a voltmeter and test the resistance before I do anything else? If I discover that its just a frayed wire, is there a quick fix?

I apologize for all of the questions, but I just want to make sure I'm going about this the right way before I drop even more money into this car (just recently dropped $$$ to replace all 8 control arms, front struts, timing, water pump etc.)

 

Well, since you have already entertained the idea to DIY, why don't you attempt to complete the job by yourself. I know you said that it seems a bit too daunting after your initial attempt but you should not let that discourage you. Even if you have to buy some tools to tackle the task, it will still end up costing you less than having either mechanic do the job.

as far as testing the voltages and whatnot, I'm not an expert, but it seems like a waste of your time at this point. you already have the replacement parts, get to replacing. I've not evaluated how much "fun" doing the O2 sensors are on the 3.0 but I assume it is pretty similar to my 2.7. I don't think you need to remove the valve covers to get at the sensors. you will need to move/remove most of the junk on top of the motor, at the back, near the firewall. Then get a bunch of extensions for your ratchet fish the sensor socket down onto the sensor. sometimes it is easier to get at it from the opposite side of the car, ie: get the passenger side sensor by going at it from the driver's side of the car and across.

good luck

 

Thanks 02A6Beau. Yea I figured the voltmeter might be a waste of time. And seeing that I'm trying to save money, the logical thing to do would be to attempt it myself again. I have a Bentley manual on the way so I'm hoping that will help me out a bit.

Does anyone else on here have experience with this issue on a 3.0? If a DIY (with pics would be great) exists could someone post a link?

I've also heard that the cats on the 3.0 tend to go out around 100-120k regardless of the 02 sensors. If that is the case, maybe I should just wait until then?