MisterG

I have been getting the P1411 & P1423 codes ever since I bought my 2000 A6 Quattro Avant, 2.8 30V.

I took it to a local Audi specialist shop. They did all of the usual - checked secondary air pump, replaced vacuum hoses, replaced plastic hose going to the combi valves from pump, checked the combi valves - and concluded that the port in the passenger side head where the combi valve is connected is clogged. They have been unable to unclog the port and were going to try one more trick, otherwise the head was going to have to come off.

Has anyone experienced anything like this on their 2.8?

I am diving in to replace the TB and all the cam seals, and figure while I have it open, I might have more access to the combi valve port. Any advice would be appreciated.

sssuperlite23

I'm having same codes come up. They appear to be do to water in the secondary air pump. Have your mechanic disconnect pressure side hose from pump. If water comes out you probably have at least one bad combi valve. It would be allowing reverse flow and bringing water from exhaust into hose which makes its way to pump. another clue to having water in pump is loud noise at cold start up. hope this helps

MisterG

No water coming out of the pressure side of the pump. Just no flow past the combi valve.

Interesting thing is tha when it is cold outside, the codes only appear very rarely. Once it warms up outside, I see the codes weekly or more often.

The shop where I took it for the problem said that it will not affect performance, but I will not pass emissions as it will never reset into ready mode.

Peter Badore

At least half of the A6s I worked on this past year have secondary air insufficient flow or other related problems.
I just delete the DTCs and since Michigan doesn't have any emission inspections most people just drive their
A6s with the fault codes present. Clogged secondary air passageways in the cylinder heads are common on other VW/Audi models. VW 2.8l VR6 engines are notorious for this problem.

audifirst

the combi valves are dirty, and when hot they stick which prevent them from functioning properly , there was write up on B5 forum, someone removed them and clean them with intake spray cleaner and lot of dirty sluge came out, and the problem was fixed, I don't think dealers will do that they replace with new set ,
I am planning to do mine soon I have more time available,

MisterG

Do you know if there is any way to unclog the heads without pulling them?

4Driver4

The heads aren't clogged. Check and replace the combi valves as required.

audifirst

here is link to guy who clean them
https://www.audiworld.com/forums/sho....php?p=2360692

MisterG

Thank you.

I will give ®obs definitive guide to fixing seconday air injection incorrect flow detected problems a try and see what I can find.

Redneck Truck

I'm not using the kombi valves anymore from my 4.2 if you need them. Check the part numbers on yours, and if mine are the same, I'll let them go for cheap. My system worked great, but I didn't like the engine bay clutter and all the extra plumbing that could fail.