Hey fellow Audi enthusiasts, I have an 2003 Audi A6 2.7T that just recently started to have a rough idle. Of course the check engine light came on and is now intermittently blinking when the idle gets rough.

I have pulled the check engine codes and check out this monster list:

P0171 System is too lean - bank 1
P0130 generic O2 circuit - bank 1 sensor 1
P0492 generic secondary air injection system - bank 2
P0135 generic O2 heater circuit - bank 1, sensor 1
P0300 random misfire detected
P0302 cylinder 2 misfire detected
P0303 cylinder 3 misfire detected
P0741 Torque converter clutch solenoid circuit performance or stuck off
P0301 Cylinder 1 misfire detected

What do you guys think I should start with replacing? The coil packs and spark plugs, or that and the O2 sensors. Does the 2003 A6 2.7T only have 3 coil packs? Could a vacuum leak also cause these problems?

Any help is appreciated.

 

Misfires on 1-2-3 (Bank 1) are likely caused by a bad Ignition Control Module (ICM) for that bank. There are 2 ICM mounted on top of the airbox (bank1 & bank2). The misfires are likely triggering the O2 codes on bank 1, but they might be unrelated. I'd suggest you check the plugs on bank 1, just to be sure they all aren't drowning in oil, due to a valve cover leak. If the cavities look clean, then swap the ICMs (B1-B2, B2-B1) & clear your codes. If misfires move to 4-5-6, then you got a bad ICM.
Since there are 2 ICM's, it's up to you if you want to change the other, since it may not be far behind. But, they are very easy to get to, so if you wnat to save the $, then only change the one. I forget which ICM go to bank 1 vs 2. Search forum postings & you should find it.

 

Thanks for the info.

I went ahead and replaced the ignition coils and spark plugs on each of the 6 cylinders. The rough idling has subsided for now. I am still get an error code with my O2 sensor (bank 2 sensor 1). Is this the sensor downstream from the catalytic converter?

I was thinking of just replacing the sensor myself, can anyone link up installation directions for an O2 replacement?

 

yeah- sounds like your O2 went as the car ran rich- search O2 on the site- plenty of DIY for this- I believe Bank 2 is passenger side- you will see a green connector on the firewall- follow it down to sensor- spray some penetrating oil to help remove-can be removed from engine compartment. note: you have 4 sensors (before and after cat)- this is before- hope this helps

 

I recall needing a crows foot O2 socket and a long extension to get these sensors off.
As mentioned, soak it with PB-blaster, cause it can be stuck in there.
Bank 2 sensor 1 is upstream from the CAT, passenger side.
Go at it from opposite side, above, thus the need for the long extension.

 

17mm crows foot or specific O2 sensor wrench will do the trick. I did the same thing - Went from above about a year ago. It was actually a lot easier than I thought.

 

So you both are saying I can reach the upstream O2 sensors on both sides from above, not having to remove my catalytic converter from below?

 

The passenger side, yes. The driver's side... That's a tight squeeze with the way the engine sits. I suppose it's possible, but you won't have much leverage to break it free.

 

I did both sides from above on a 2000 A6 2.7
I had a deep O2 socket, w/ the slot on the side for the wire, but the O2 sensor had a rigid part of the lead that prevented getting it to turn out the side slot. The crows foot worked for me. Nebuchadnezzar's comment reminded me that the DS was more difficult. I think I got inventive using combination a crows foot, U joint, 1/2" & 3/8" extensions. I remember it was also difficult to get the PB blaster spray to it. A long shot, & I'm a bad aim. I resorted to spraying it in some flex tubing & let gravity take it down to the O2 sensor. When you put new one on, wipe the surface clean & use anti-seize on the threads. Some O2's come with anti-seize, but if not, add it. Saving yourself or the next guy a headache.