That really depends on the size of the leak but does need to be really close to the o2 sensor in question. Normally they are before it normally caused by broken exhaust studs.
Well, BINGO. I did have at least one broken stud. One was spinning around. I believe the tech replaced it. I'll have to take a closer look. Do the exhaust manifolds need to come off to repair the studs? They have +250,000 miles on them.
Depends on if they come out of the head easily or not. On most BMW's I don't have problems but if one is really stuck then yes the manifolds do need to come partially off.
Getting closer. Bank 1 voltage precat sensor was a constant .9x volts at idle. Bank 2 fluctuated as normal at idle. Both sensors operated normally while driving. Swapped bank 1 sensor for bank 2 and my problem moved telling me it's a bad sensor. Hard to tell what happened. It was new although I did have work done to the car. So now it's off to buy another sensor.
Replaced pre 02 sensor. Cleared codes. Voltages now fluctuating at idle as they should be. I've gotten used to seeing my car on jack stands. I'm getting fast at swapping 02 sensors. I've been using http://www.scantool.net/scan-tools/smart-phone/obdlink-mx.html with my Nexus 7 and Galaxy 3. Really makes the Peake Tool worthless. Next project, bleed air from the cooling system on my E30.
