2004 secondary air injection system
 

This guy posted back in Sept and got ZERO reply. I have a 2003 with same problem. I have an 04 allroad... The check engine light is on and the code is p0492.. There is no sound like a vacuum like others describe... How do I fix this!? Help!
In my car all the visible and reachable connections have been checked and seem OK. Hate to replace the pump but how else can I diagnose what the problem is?

Your secondary air is a system made to help ignite your converts faster for emissions. If your air pump isn't running then it can throw the code. If the line from the pump to the head is cracked/broken clogged it can throw the code. Your Evap purge Valve -N80- or Air solenoid Valve -N112- can be shorted/sticky. P0492 is a flow problem for bank 2 (driver side). Testing this system to find the exact problem does require for then a code reader for this problem so i would recommend you let a dealer look at it or a European specialty shop look at it otherwise throw parts at it can get expensive fast

More than likely the Kombi Valve hoses off the main spider are loose or cracked. VAG-COM will show codes and they will need to be addressed.

The most common cause of sec air flow faults is the vac hoses perished, on the combi valves. The combi valve is bolted onto the back of the cyl head of each bank. From my experience another cause is when the air filter housing has been disturbed, then the air supply pipe on it ,which runs down to the sec air flow pump, gets left off or not refitted correctly.

The pump is dead, it corroded up from water vapor coming in through the valve and froze the motor taking out the fuse as well. Is there a way to get the CEL to extinguish without replacing all those parts?

No there is not. You can clear the code but on the second cold start (usually needs to "see" the fault twice before setting a code), it'll be back along with the CEL.

May have been mentioned earlier, the most common cause of an air pump failure is leaky combi-valves (OK,,, Kombi Valve) allowing exhaust with it's acidic moisture into the fresh air side of the system. Actually, guess you were the one that mentioned it already.

what is the least expensive way to get rid of the CEL. The dealer wants way too much money to fix this problem

First you'll need to determine which (or both) combi-valve is leaking exhaust back into the air injection system. Usually only one will be bad but not always.

I'd get a combi-valve (or valves) from a non-dealer vendor (check ebay, one of the places that advertises here, etc) and then either replace the parts yourself or find a good indy shop that can do it. Be sure they're familiar with European cars. Used parts are OK as long as they can be verified as GOOD used parts before installing. Pump can be tested with jumpers and the valves should not flow without vacuum applied and should flow with vacuum. They can fail either way (leak or not open at all).The pump is fairly easy to swap. The combi-valves are a little more of a PITA due to the location. You need a small allen bit and ratchet driver for access pretty much. Not a 1/4" ratchet but a ratchet bit driver tool. Be sure to carefully inspect the vacuum hoses or better yet, replace them. On that I'd really recommend the OEM style hose with the braided covering vs parts store stuff. The covered hose is one thing well worth the added cost, trust me.

Then change the fuse and start the car (cold engine). You should hear the pump run for a short time. On a 2.7L they make a racket, being mounted on the rear of the engine, right next to the firewall. Then the fault codes will need to be cleared. The light will go out on it's own eventually but normally would take 40 cold start/drive cycles (means cold start, fully warm and fully cooled again 40 times).

Here's what I mean by ratcheting bit driver:

The secondary air pump was frozen as mentioned. I now have it removed from the car. Somebody on ebay is rebuilding your bad pump and sending it back for $99. Has anyone used this service? I know there is also a detailed posting with photos in the forum for those who want to DIY but I want to know if anyone has used the guy on ebay? Or should I just leave it off and ignore the CEL

Replace the bad pump (not a bad job); I have take offs here.
Or tune out. If tuning: may as well tune out the SAI (if not emissions: also downstream O2 sensor; cat or sensor will go bad sooner or later, EGT sensors (expansive to replace)) AND get a stage 1 tune.