Air Injection Circuit
 

My check engine was throwing a fault code that had to do with Air Injection Circuit bank one and two. Mechanic thinks I may need a new air pump, I think he said (maybe $350?)
Anyone with experience on this little problem? an EZ fix perhaps?
I had read in the archives that the may possibly be hoses getting too hot from engine heat.
Anyway the lamp was reset, but will probably go back on sometime soon from what he said.
Any and all help appreciated:)
Thanks much.
Bill m

What's an air pump?
 

I don't know what you are referring to when you say air pump. Not to say the A8 doesn't have one, I just never heard of it.

Do you know the fault code? If so, post it and we can help you out....or just hope it comes back by Saturday. :-)

pw

The air pump is located ...
 

.
inside the main air filter housing, even though it has it's own air filter.

It's called the "secondary pump" (engine is primary pump?) and pumps filtered air into the exhaust port of each exhaust valve for 60-90 seconds on start-up if coolant temperature is between 0 and 50 oC. The only purpose of the extra air is to help heat up the catalytic converters more quickly when the mixture is rich and before the Lambda sensors are up to operating temperature.

Downstream of the pump there is a "combination valve" for each bank that prevents exhaust gases from flowing backwards thru the pump and damaging it. I guess these could be bad rather than the air pump, though it seems unlikely that both would have failed.

Replacing the pump should be very easy, though ~$350 for a little electrical air pump sounds a bit steep.

Re: What's an air pump?
 

Thanks Randy & Paul,
I believe the codes for this are 17819 p1411 for bank 2 and 17831 p1423 for bank 2. If that makes any sense. If not I'll be back in town friday and call the mechanic and see if he remembers. I'll have to explore Bentley a little.
So far no check engine light but I would expect it to return in time. Mechanic said it may ultimately foul the cats but the stupid dealer overfilling with oil would probably do that in time too.
Got to drive the car today.. like a limo compared to the S6. Both great just different:)
Thanx again guys!
Bill m

Can this secondary pump...
 

Cause engine vibration? and is this the same pump has can potentially cause the squealling i mentioned in another post "Squeal Part III", or is that another pump in the transmission?

I can't imagine how this could cause engine vibration, but ...
 

.
it could definitely explain the <A HREF="https://forums.audiworld.com/a8/msgs/18769.phtml">Squeal Part III</a> or the <A HREF="https://forums.audiworld.com/a8/msgs/19286.phtml">Winding Noise</a>.

The pump runs for 60 to 90 sec on cold starts when idling, but it also shuts off after a defined mass of air has gone thru the motor (as measured by the main fuel injection system mass meter).

I doubt that a pump failure would foul the cats or cause any other damage. I believe this secondary air gimmick is only used because the tailpipes of cars have gotten so clean that most auto air "pollution" now occurs only during that time before the cats are up to operating temperature. A few years ago, this trick wasn't used on cars at all and didn't cause any problems with the cats or anything else.

Check this..........
 

when You open your hood and stand in front off your car you should see two vacum lines coming out underneith your bank two camshaft cover.Those lines lead to your vacum reservoirs for air system and they used to crack right next to reservoir.You can't see reservoirs but yuo can try to pull on those vacum lines slightly to se if they are still conected. Best way would be checking with vacum pump.