I have a 99 A6 2.8L, I've replaced the coil pack, the spark plugs, and the air vent tubing. I get the following codes:
P0157 o2 circuit low voltage bank2, sensor2
P0300 random misfire
P0303 cylinder 3 misfire
P0305 cylinder 5 misfire

My next step is checking the ignition coil since 3&5 are are the same wire. My question is what am I checking for and how? The manual I've been doing my work from is for passat/audi a4 but covers the 2.8L but the wiring diagrams/schematics are a little different. Also is there a fuse or something else I should be checking.

Thanks for the help

 

Does the engine shake?

Try;

Ross-Tech: VCDS: Diagnostic Procedures

Category:Fault Codes - Ross-Tech Wiki

 

It does at low rpm, after 2 1/2 to 3ish it seems fine. Every once in a while it will in higher gears but still at the lower range of rpm.

 

figured it out, the new coil pack I got was bad the pack that controls cylinder 3 & 5 was a couple thousand ohms out of tolerance. Just got a new one from Audi and now no problem.

 

That was a result I had same sort of issue in my 2000 a3 number 3 wasn't getting power even after bridging it to a live still ran like crap turned out to be ignition module on air box or ignition amplifier depends what car parts shop you go