Secondary Air System Faults

I'm getting codes 0491 & 0492 which are right and left bank secondary air system failures.
Once the engine is warm, if i clear the code. They don't come back.
If it is really cold, I get the code shortly after starting, but again if I clear it, it won;t come back.
Without Audi specific test equipment, what can I do to trouble shoot?
Fuse is good, vacuum lines all look good.
The other components are the blower, ECM, Solinoid, combi-valves. I get both the righ and left banks so I believe it to be a fault in a part of the system that will throw both faults. Don;t think it could be a simultaneous right and left combi-valve failure.
No other codes. 2001 A8L, 4.2L AUX Engine.
Any thoughts?
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If the Secondary Air Pumps are low then I would guess water or ice in the system stopping air flow possibly due to other issues.

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wrote:

Had the same problem on my 2000 A6 2.7T. In my case it was the sucker valve (vacuum booster valve). This caused condensation to build up in the PCV and secondary air system which froze when it got cold. The valve I spkoe of is only on the 2.7 and 2.8 engines (I believe) but you probably have the same condition. I went through 2 secondary air pumps too.
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There is a recall on failures with this system on some of the 2.8 years and possible others. Even if you year is not covered it still should be covered because it is a component of the pollution control system. My son had his repaired a year ago at the dealer at no cost. It was an A4 '98.5 2.8. (replaced with an '06 A4 2.0TQ6M)
Jims Audi wrote:

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