gadgetmeister2711

Keep setting these codes:
p1423 & p1411 Insufficient airflow.

I've been through the entire system, all hoses, solenoid valve, Kombi valves, ETC. are functioning properly. Pump runs, Output tests activate the solenoid & pump, R&R'd the kombi valves & cleaned with brake clean.

THE QUESTION:

What does the computer actually monitor to determine if airflow is sufficient or not?
Any help is greatly appreciated

Bracketracer

how do you know for sure that the combi-valves are functioning properly? Brake cleaner typically won't fix a sticking valve. Also...you're positive that the pressure hoses are intact?

gadgetmeister2711

I disconnected the hose from the air pump, and with no vacuum applied to the Kombi-valves, i could not blow air through the system. Applied vacuum to the valves and air would pass. Tested them both together and individually. So, the pressure hose from the pump to the Kombi valves is intact, or else it wouldn't hold pressure, and the valves do open and pass air when vacuum is applied to them.

Only uncertainty I have is how easily the Kombi valves should pass air.With vacuum applied, it still takes a little pressure to blow through them. Not like a wide open passage.
Quite an expensive "Maybe this will fix it".

powerplant9

troubleshooting process. I have been living with the check engine light knowing the secondary air system is no biggie but I get sick of that light if you know what I mean.

Bracketracer

First off, the combis should pass air very easily. However, you could have carbon buildup elsewhere in the pressure passages. This is not so easy to fix.

powerplant9

I tried to blow out the holes where the combi's attach to the heads.

My guess is that these are plugged.

Is there any possible way to get rid of the engine light? I have found some threads on eliminating the air pump with a resistor but they were not very detailed. I assume there is something else that is causing the engine light? Is there a trick to override this?

Bankser

I'm also having this problem on my 2000 A6 2.7T. NC won't pass emissions with the CEL on.

Haven't had it in the shop yet but other forums seem to point to kinked hoses as the most common culprit.

Any advice on fixing or shutting off the light would be appreciated.

Bracketracer

first off, the only way to turn off the light is to fix it.

to fix it:
make sure the following parts are functioning/intact

1)2nd air fuse
2)2nd air solenoid valve
3)vacuum hoses from valve to check valve to combi valves
4)2nd air pump (does it run and push air?)
5)pressure hoses from pump to combi-valves
6)combi-valves (do they open?) (all the way?)

one of the preceding items will be the problem.