2000 A6 2.7T

I have been getting some codes that point to the secondary air system (researched them before... I think they show up on my code reader like "aux. ev. control syst." with a number I forget.... anyway... I asked on one of the forums and it is the secondary air system).

I clear the code every time and would think that it would happen each time I start the car when it is cold.. but this does not happen every time I start the car when it is cold. Sometimes I only get the 2 codes (both banks I think) that point to the secondary air system..... sometimes I will get those codes and a 3rd code that says something like low startup catalist temp.

I find it hard to believe that both combi valves are bad at the same time.

What is going on? I have looked over the vac. lines for this system and did find some leaks but I thought I cured them all.... I even removed and looked at the passenger combi valve and it looked ok.... I listen for the secondary air pump to start and I think I hear it start each time.... I don't get it....

What sensor is reading the activation and operation of this system?

Any advice?

 

The ecm uses the oxygen sensors to detmine whether the secondary air system is functioning correctly. Was there any carbon buildup in the valve. Sometimes that can cause intermitant faults.

 

I would assume that the ecm would tell me if a O2 sensor was bad? I guess that I need to keep looking at the combi valves?

 

Your correct in assuming that its not the oxygen sensors. You would get a fault and its unlikly that both would go bad at the same time.

Its also unlikely that both combi valves would go bad at the same time. I wouldnt overlook carbon buildup in the valves as it would build up the same in both valves however your problem probably lies elsewhere. There could be a problem with the control solenoid for the vacuum or the pump. The pumps relay could also be sticking. Another thing to worry about is the diverter valves. A ruptured diaphram in the diverter valves can cause the issues you describe. Get a vacuum pump and see if the valves are holding vacuum. You can also use it to check the diaphram in the combi valves.

 

Where is the pump relay? I think I am going to start by swapping that out since it is easy.

I never considered the diverter valves..... I guess I don't understand how they are related to that system but I will take your word for it. For testing the diverter valves and the combi valves I would assume that I hook up my mighty vac to each of them......pump it up and watch for any loss in vaccume?

I know it is not the solenoid as I also have a 03 allroad 2.7T. I swaped that part and I still have the same problem. I could keep swaping parts but I would rather try to figure this out with my brain that by chance.

Hang in there with me... I appreciate your help.

 

I tested both diverter valves and both combi valves with my mighty vac and they appear to have no leakage.

I need to find out where the pump relay is.... I can swap them between my cars to see if that is the problem or not.

 

Oh yea... for some reason I hit the report button thinking I was replying to this thread.... It was not my intention to report anything.... only typing technical stuff so I hope the mods realized my mistake and disregarded my report.

 

I think its in the ecm box. Do you have a vag com? You can run the relay test see where it clicks at.

 

For as many German cars as I have had.... I wish I would have invested in a VAG COM ..... in so many words .... no I don't have one.

ECM box? What is that and where is it?

Would this be in the same location as my 03 Allroad? I am thinking I will just swap the relays.

 

a few different types here

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