Hey all, I have a 2000 A6 Audi Quattro with a 2.8 (Great car great condition, which I bought new in 1999)

This is the second engine, with the first engine going, because I didn't change the timing belt when I should have (stupid me)

With the first engine the CHECK ENGINE light wouldn't go out even after numerous trips to the dealership and this included the main computer board being replaced because some mice decided to build a nest under the engine cover to stay warm in the winter and fed on the engine main wiring harness.

Anyway the main computer in the engine bay was replaced, but the check engine light would not go off or reset at the dealer... the dealer told me that it was an air sensor in the head and it would have to be replace when the heads were rebuilt... so I decided to live with it.

About 4 months later the timing belt let loose taking out the valves and at that point it was cheeper putting in a used 2.8 engine with 35,000 miles on in stead of having my 80,000+ mile motor rebuilt.

So with the new used motor I thought the CHECK ENGINE light would go off... AND NO IT DIDN'T. (So no it wasn't what the dealer said it was)

Recently I had the engine codes checked and the two error codes that coming up were P0411 (Secondary Air Injection System Incorrect Flow Detected) and
P0306 (Cylinder 6 Misfire Detected) (Which is strange because the engine runs real smooth)

The question I have is what might be causing the above codes?

I also tried reseting the CHECK ENGINE light by disconnecting the battery cable for 10 minutes but the light is still on.

Any thoughts from someone in the know?

 

check your Kombi valve and your vacuum lines The valve is actuated by vacuum lines so if you have old lines that are cracked replace them all. If one is cracked they are all shot.
Cheap and easy to replace.

You may just be getting a misfire on start up and then it goes away or a little bit at WOT and you not feeling it.

If you getting a code set it's misfiring a lot though.

 

Do you have your own VagCom? If not it's time you got your own.

+1 on the vacuum lines and combi valve. Start with the lines.

Once that is done clear the codes with VagCom and see what returns. you can't clear them by disconnecting the battery -ya need VagCom.

Do a search in this forum on RossTech or VagCom and you'll see how to get one for almost free if you have a lap top or computer close to the garage.

 

Man.... that Kombi valve is back there! I was just looking at it and there is like no room in the back of the cylinder heads to play.

I'll check the hoses and replace them as recommended... also how can I check the Kombi valves?

thanks.

 

Thanks and I'm checking the hoses now... I'll report back.

Checked on VagCom and it's $500 with software and cables.... ouch!

 

You need to look a bit deeper

1. Do a search in this forum and You'll see that there is an almost free VagCom.

2. Get a Bentley manual for your vehicle -- If your looking at the back of the motor your about 180 degrees off...

 

+1

The combination valve (EGR Valve) is at the front of the engine. It looks like this.

 

Really the Vac lines are probably 100 times more likely to crack and fail especially on a car of that age. If they are old just order a 5 meter roll from www.ecstuning.com . I get the braided line-like OEM. It's easier to start diagnostics when you know the maintenance is up to date. otherwise it could be a ton of little nonsense creating one problem.

Definitely score a vag-com so you can pull the actual codes yourself and a bentley manual to help diagnose your problems. You'll get real good at dignostics with this car. Like it or not.